diff --git a/src/sessions.ts b/src/sessions.ts
index bd10e7e07c7..1fc88b468f4 100644
--- a/src/sessions.ts
+++ b/src/sessions.ts
@@ -46,7 +46,7 @@ import {
   squashError,
   uuidV4
 } from './utils';
-import { WriteConcern } from './write_concern';
+import { WriteConcern, type WriteConcernOptions, type WriteConcernSettings } from './write_concern';
 
 const minWireVersionForShardedTransactions = 8;
 
@@ -443,14 +443,167 @@ export class ClientSession
    * Commits the currently active transaction in this session.
    */
   async commitTransaction(): Promise<void> {
-    return await endTransaction(this, 'commitTransaction');
+    if (this.transaction.state === TxnState.NO_TRANSACTION) {
+      throw new MongoTransactionError('No transaction started');
+    }
+
+    if (
+      this.transaction.state === TxnState.STARTING_TRANSACTION ||
+      this.transaction.state === TxnState.TRANSACTION_COMMITTED_EMPTY
+    ) {
+      // the transaction was never started, we can safely exit here
+      this.transaction.transition(TxnState.TRANSACTION_COMMITTED_EMPTY);
+      return;
+    }
+
+    if (this.transaction.state === TxnState.TRANSACTION_ABORTED) {
+      throw new MongoTransactionError(
+        'Cannot call commitTransaction after calling abortTransaction'
+      );
+    }
+
+    const command: {
+      commitTransaction: 1;
+      writeConcern?: WriteConcernSettings;
+      recoveryToken?: Document;
+      maxTimeMS?: number;
+    } = { commitTransaction: 1 };
+
+    const wc = this.transaction.options.writeConcern ?? this.clientOptions?.writeConcern;
+    if (wc != null) {
+      WriteConcern.apply(command, { wtimeoutMS: 10000, w: 'majority', ...wc });
+    }
+
+    if (this.transaction.state === TxnState.TRANSACTION_COMMITTED) {
+      WriteConcern.apply(command, { wtimeoutMS: 10000, ...wc, w: 'majority' });
+    }
+
+    if (typeof this.transaction.options.maxTimeMS === 'number') {
+      command.maxTimeMS = this.transaction.options.maxTimeMS;
+    }
+
+    if (this.transaction.recoveryToken) {
+      command.recoveryToken = this.transaction.recoveryToken;
+    }
+
+    const operation = new RunAdminCommandOperation(command, {
+      session: this,
+      readPreference: ReadPreference.primary,
+      bypassPinningCheck: true
+    });
+
+    try {
+      await executeOperation(this.client, operation);
+      return;
+    } catch (firstCommitError) {
+      if (firstCommitError instanceof MongoError && isRetryableWriteError(firstCommitError)) {
+        // SPEC-1185: apply majority write concern when retrying commitTransaction
+        WriteConcern.apply(command, { wtimeoutMS: 10000, ...wc, w: 'majority' });
+        // per txns spec, must unpin session in this case
+        this.unpin({ force: true });
+
+        try {
+          await executeOperation(this.client, operation);
+          return;
+        } catch (retryCommitError) {
+          // If the retry failed, we process that error instead of the original
+          if (shouldAddUnknownTransactionCommitResultLabel(retryCommitError)) {
+            retryCommitError.addErrorLabel(MongoErrorLabel.UnknownTransactionCommitResult);
+          }
+
+          if (shouldUnpinAfterCommitError(retryCommitError)) {
+            this.unpin({ error: retryCommitError });
+          }
+
+          throw retryCommitError;
+        }
+      }
+
+      if (shouldAddUnknownTransactionCommitResultLabel(firstCommitError)) {
+        firstCommitError.addErrorLabel(MongoErrorLabel.UnknownTransactionCommitResult);
+      }
+
+      if (shouldUnpinAfterCommitError(firstCommitError)) {
+        this.unpin({ error: firstCommitError });
+      }
+
+      throw firstCommitError;
+    } finally {
+      this.transaction.transition(TxnState.TRANSACTION_COMMITTED);
+    }
   }
 
   /**
    * Aborts the currently active transaction in this session.
    */
   async abortTransaction(): Promise<void> {
-    return await endTransaction(this, 'abortTransaction');
+    if (this.transaction.state === TxnState.NO_TRANSACTION) {
+      throw new MongoTransactionError('No transaction started');
+    }
+
+    if (this.transaction.state === TxnState.STARTING_TRANSACTION) {
+      // the transaction was never started, we can safely exit here
+      this.transaction.transition(TxnState.TRANSACTION_ABORTED);
+      return;
+    }
+
+    if (this.transaction.state === TxnState.TRANSACTION_ABORTED) {
+      throw new MongoTransactionError('Cannot call abortTransaction twice');
+    }
+
+    if (
+      this.transaction.state === TxnState.TRANSACTION_COMMITTED ||
+      this.transaction.state === TxnState.TRANSACTION_COMMITTED_EMPTY
+    ) {
+      throw new MongoTransactionError(
+        'Cannot call abortTransaction after calling commitTransaction'
+      );
+    }
+
+    const command: {
+      abortTransaction: 1;
+      writeConcern?: WriteConcernOptions;
+      recoveryToken?: Document;
+    } = { abortTransaction: 1 };
+
+    const wc = this.transaction.options.writeConcern ?? this.clientOptions?.writeConcern;
+    if (wc != null) {
+      WriteConcern.apply(command, { wtimeoutMS: 10000, w: 'majority', ...wc });
+    }
+
+    if (this.transaction.recoveryToken) {
+      command.recoveryToken = this.transaction.recoveryToken;
+    }
+
+    const operation = new RunAdminCommandOperation(command, {
+      session: this,
+      readPreference: ReadPreference.primary,
+      bypassPinningCheck: true
+    });
+
+    try {
+      await executeOperation(this.client, operation);
+      this.unpin();
+      return;
+    } catch (firstAbortError) {
+      this.unpin();
+
+      if (firstAbortError instanceof MongoError && isRetryableWriteError(firstAbortError)) {
+        try {
+          await executeOperation(this.client, operation);
+          return;
+        } catch (secondAbortError) {
+          // we do not retry the retry
+        }
+      }
+
+      // The spec indicates that if the operation times out or fails with a non-retryable error, we should ignore all errors on `abortTransaction`
+    } finally {
+      this.transaction.transition(TxnState.TRANSACTION_ABORTED);
+      if (this.loadBalanced) {
+        maybeClearPinnedConnection(this, { force: false });
+      }
+    }
   }
 
   /**
@@ -496,25 +649,132 @@ export class ClientSession
     fn: WithTransactionCallback<T>,
     options?: TransactionOptions
   ): Promise<T> {
+    const MAX_TIMEOUT = 120000;
     const startTime = now();
-    return await attemptTransaction(this, startTime, fn, options);
+
+    let committed = false;
+    let result: any;
+
+    while (!committed) {
+      this.startTransaction(options); // may throw on error
+
+      try {
+        const promise = fn(this);
+        if (!isPromiseLike(promise)) {
+          throw new MongoInvalidArgumentError(
+            'Function provided to `withTransaction` must return a Promise'
+          );
+        }
+
+        result = await promise;
+
+        if (
+          this.transaction.state === TxnState.NO_TRANSACTION ||
+          this.transaction.state === TxnState.TRANSACTION_COMMITTED ||
+          this.transaction.state === TxnState.TRANSACTION_ABORTED
+        ) {
+          // Assume callback intentionally ended the transaction
+          return result;
+        }
+      } catch (fnError) {
+        if (!(fnError instanceof MongoError) || fnError instanceof MongoInvalidArgumentError) {
+          await this.abortTransaction();
+          throw fnError;
+        }
+
+        if (
+          this.transaction.state === TxnState.STARTING_TRANSACTION ||
+          this.transaction.state === TxnState.TRANSACTION_IN_PROGRESS
+        ) {
+          await this.abortTransaction();
+        }
+
+        if (
+          fnError.hasErrorLabel(MongoErrorLabel.TransientTransactionError) &&
+          now() - startTime < MAX_TIMEOUT
+        ) {
+          continue;
+        }
+
+        throw fnError;
+      }
+
+      while (!committed) {
+        try {
+          /*
+           * We will rely on ClientSession.commitTransaction() to
+           * apply a majority write concern if commitTransaction is
+           * being retried (see: DRIVERS-601)
+           */
+          await this.commitTransaction();
+          committed = true;
+        } catch (commitError) {
+          /*
+           * Note: a maxTimeMS error will have the MaxTimeMSExpired
+           * code (50) and can be reported as a top-level error or
+           * inside writeConcernError, ex.
+           * { ok:0, code: 50, codeName: 'MaxTimeMSExpired' }
+           * { ok:1, writeConcernError: { code: 50, codeName: 'MaxTimeMSExpired' } }
+           */
+          if (
+            !isMaxTimeMSExpiredError(commitError) &&
+            commitError.hasErrorLabel(MongoErrorLabel.UnknownTransactionCommitResult) &&
+            now() - startTime < MAX_TIMEOUT
+          ) {
+            continue;
+          }
+
+          if (
+            commitError.hasErrorLabel(MongoErrorLabel.TransientTransactionError) &&
+            now() - startTime < MAX_TIMEOUT
+          ) {
+            break;
+          }
+
+          throw commitError;
+        }
+      }
+    }
+
+    return result;
   }
 }
 
 configureResourceManagement(ClientSession.prototype);
 
-const MAX_WITH_TRANSACTION_TIMEOUT = 120000;
 const NON_DETERMINISTIC_WRITE_CONCERN_ERRORS = new Set([
   'CannotSatisfyWriteConcern',
   'UnknownReplWriteConcern',
   'UnsatisfiableWriteConcern'
 ]);
 
-function hasNotTimedOut(startTime: number, max: number) {
-  return calculateDurationInMs(startTime) < max;
+function shouldUnpinAfterCommitError(commitError: Error) {
+  if (commitError instanceof MongoError) {
+    if (
+      isRetryableWriteError(commitError) ||
+      commitError instanceof MongoWriteConcernError ||
+      isMaxTimeMSExpiredError(commitError)
+    ) {
+      if (isUnknownTransactionCommitResult(commitError)) {
+        // per txns spec, must unpin session in this case
+        return true;
+      }
+    } else if (commitError.hasErrorLabel(MongoErrorLabel.TransientTransactionError)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+function shouldAddUnknownTransactionCommitResultLabel(commitError: MongoError) {
+  let ok = isRetryableWriteError(commitError);
+  ok ||= commitError instanceof MongoWriteConcernError;
+  ok ||= isMaxTimeMSExpiredError(commitError);
+  ok &&= isUnknownTransactionCommitResult(commitError);
+  return ok;
 }
 
-function isUnknownTransactionCommitResult(err: MongoError) {
+function isUnknownTransactionCommitResult(err: MongoError): err is MongoError {
   const isNonDeterministicWriteConcernError =
     err instanceof MongoServerError &&
     err.codeName &&
@@ -569,282 +829,17 @@ export function maybeClearPinnedConnection(
   }
 }
 
-function isMaxTimeMSExpiredError(err: MongoError) {
+function isMaxTimeMSExpiredError(err: MongoError): boolean {
   if (err == null || !(err instanceof MongoServerError)) {
     return false;
   }
 
   return (
     err.code === MONGODB_ERROR_CODES.MaxTimeMSExpired ||
-    (err.writeConcernError && err.writeConcernError.code === MONGODB_ERROR_CODES.MaxTimeMSExpired)
+    err.writeConcernError?.code === MONGODB_ERROR_CODES.MaxTimeMSExpired
   );
 }
 
-async function attemptTransactionCommit<T>(
-  session: ClientSession,
-  startTime: number,
-  fn: WithTransactionCallback<T>,
-  result: T,
-  options: TransactionOptions
-): Promise<T> {
-  try {
-    await session.commitTransaction();
-    return result;
-  } catch (commitErr) {
-    if (
-      commitErr instanceof MongoError &&
-      hasNotTimedOut(startTime, MAX_WITH_TRANSACTION_TIMEOUT) &&
-      !isMaxTimeMSExpiredError(commitErr)
-    ) {
-      if (commitErr.hasErrorLabel(MongoErrorLabel.UnknownTransactionCommitResult)) {
-        return await attemptTransactionCommit(session, startTime, fn, result, options);
-      }
-
-      if (commitErr.hasErrorLabel(MongoErrorLabel.TransientTransactionError)) {
-        return await attemptTransaction(session, startTime, fn, options);
-      }
-    }
-
-    throw commitErr;
-  }
-}
-
-const USER_EXPLICIT_TXN_END_STATES = new Set<TxnState>([
-  TxnState.NO_TRANSACTION,
-  TxnState.TRANSACTION_COMMITTED,
-  TxnState.TRANSACTION_ABORTED
-]);
-
-function userExplicitlyEndedTransaction(session: ClientSession) {
-  return USER_EXPLICIT_TXN_END_STATES.has(session.transaction.state);
-}
-
-async function attemptTransaction<T>(
-  session: ClientSession,
-  startTime: number,
-  fn: WithTransactionCallback<T>,
-  options: TransactionOptions = {}
-): Promise<T> {
-  session.startTransaction(options);
-
-  let promise;
-  try {
-    promise = fn(session);
-  } catch (err) {
-    promise = Promise.reject(err);
-  }
-
-  if (!isPromiseLike(promise)) {
-    try {
-      await session.abortTransaction();
-    } catch (error) {
-      squashError(error);
-    }
-    throw new MongoInvalidArgumentError(
-      'Function provided to `withTransaction` must return a Promise'
-    );
-  }
-
-  try {
-    const result = await promise;
-    if (userExplicitlyEndedTransaction(session)) {
-      return result;
-    }
-    return await attemptTransactionCommit(session, startTime, fn, result, options);
-  } catch (err) {
-    if (session.inTransaction()) {
-      await session.abortTransaction();
-    }
-
-    if (
-      err instanceof MongoError &&
-      err.hasErrorLabel(MongoErrorLabel.TransientTransactionError) &&
-      hasNotTimedOut(startTime, MAX_WITH_TRANSACTION_TIMEOUT)
-    ) {
-      return await attemptTransaction(session, startTime, fn, options);
-    }
-
-    if (isMaxTimeMSExpiredError(err)) {
-      err.addErrorLabel(MongoErrorLabel.UnknownTransactionCommitResult);
-    }
-
-    throw err;
-  }
-}
-
-async function endTransaction(
-  session: ClientSession,
-  commandName: 'abortTransaction' | 'commitTransaction'
-): Promise<void> {
-  // handle any initial problematic cases
-  const txnState = session.transaction.state;
-
-  if (txnState === TxnState.NO_TRANSACTION) {
-    throw new MongoTransactionError('No transaction started');
-  }
-
-  if (commandName === 'commitTransaction') {
-    if (
-      txnState === TxnState.STARTING_TRANSACTION ||
-      txnState === TxnState.TRANSACTION_COMMITTED_EMPTY
-    ) {
-      // the transaction was never started, we can safely exit here
-      session.transaction.transition(TxnState.TRANSACTION_COMMITTED_EMPTY);
-      return;
-    }
-
-    if (txnState === TxnState.TRANSACTION_ABORTED) {
-      throw new MongoTransactionError(
-        'Cannot call commitTransaction after calling abortTransaction'
-      );
-    }
-  } else {
-    if (txnState === TxnState.STARTING_TRANSACTION) {
-      // the transaction was never started, we can safely exit here
-      session.transaction.transition(TxnState.TRANSACTION_ABORTED);
-      return;
-    }
-
-    if (txnState === TxnState.TRANSACTION_ABORTED) {
-      throw new MongoTransactionError('Cannot call abortTransaction twice');
-    }
-
-    if (
-      txnState === TxnState.TRANSACTION_COMMITTED ||
-      txnState === TxnState.TRANSACTION_COMMITTED_EMPTY
-    ) {
-      throw new MongoTransactionError(
-        'Cannot call abortTransaction after calling commitTransaction'
-      );
-    }
-  }
-
-  // construct and send the command
-  const command: Document = { [commandName]: 1 };
-
-  // apply a writeConcern if specified
-  let writeConcern;
-  if (session.transaction.options.writeConcern) {
-    writeConcern = Object.assign({}, session.transaction.options.writeConcern);
-  } else if (session.clientOptions && session.clientOptions.writeConcern) {
-    writeConcern = { w: session.clientOptions.writeConcern.w };
-  }
-
-  if (txnState === TxnState.TRANSACTION_COMMITTED) {
-    writeConcern = Object.assign({ wtimeoutMS: 10000 }, writeConcern, { w: 'majority' });
-  }
-
-  if (writeConcern) {
-    WriteConcern.apply(command, writeConcern);
-  }
-
-  if (commandName === 'commitTransaction' && session.transaction.options.maxTimeMS) {
-    Object.assign(command, { maxTimeMS: session.transaction.options.maxTimeMS });
-  }
-
-  if (session.transaction.recoveryToken) {
-    command.recoveryToken = session.transaction.recoveryToken;
-  }
-
-  try {
-    // send the command
-    await executeOperation(
-      session.client,
-      new RunAdminCommandOperation(command, {
-        session,
-        readPreference: ReadPreference.primary,
-        bypassPinningCheck: true
-      })
-    );
-    if (command.abortTransaction) {
-      // always unpin on abort regardless of command outcome
-      session.unpin();
-    }
-    if (commandName !== 'commitTransaction') {
-      session.transaction.transition(TxnState.TRANSACTION_ABORTED);
-      if (session.loadBalanced) {
-        maybeClearPinnedConnection(session, { force: false });
-      }
-    } else {
-      session.transaction.transition(TxnState.TRANSACTION_COMMITTED);
-    }
-  } catch (firstAttemptErr) {
-    if (command.abortTransaction) {
-      // always unpin on abort regardless of command outcome
-      session.unpin();
-    }
-    if (firstAttemptErr instanceof MongoError && isRetryableWriteError(firstAttemptErr)) {
-      // SPEC-1185: apply majority write concern when retrying commitTransaction
-      if (command.commitTransaction) {
-        // per txns spec, must unpin session in this case
-        session.unpin({ force: true });
-
-        command.writeConcern = Object.assign({ wtimeout: 10000 }, command.writeConcern, {
-          w: 'majority'
-        });
-      }
-
-      try {
-        await executeOperation(
-          session.client,
-          new RunAdminCommandOperation(command, {
-            session,
-            readPreference: ReadPreference.primary,
-            bypassPinningCheck: true
-          })
-        );
-        if (commandName !== 'commitTransaction') {
-          session.transaction.transition(TxnState.TRANSACTION_ABORTED);
-          if (session.loadBalanced) {
-            maybeClearPinnedConnection(session, { force: false });
-          }
-        } else {
-          session.transaction.transition(TxnState.TRANSACTION_COMMITTED);
-        }
-      } catch (secondAttemptErr) {
-        handleEndTransactionError(session, commandName, secondAttemptErr);
-      }
-    } else {
-      handleEndTransactionError(session, commandName, firstAttemptErr);
-    }
-  }
-}
-
-function handleEndTransactionError(
-  session: ClientSession,
-  commandName: 'abortTransaction' | 'commitTransaction',
-  error: Error
-) {
-  if (commandName !== 'commitTransaction') {
-    session.transaction.transition(TxnState.TRANSACTION_ABORTED);
-    if (session.loadBalanced) {
-      maybeClearPinnedConnection(session, { force: false });
-    }
-    // The spec indicates that if the operation times out or fails with a non-retryable error, we should ignore all errors on `abortTransaction`
-    return;
-  }
-
-  session.transaction.transition(TxnState.TRANSACTION_COMMITTED);
-  if (error instanceof MongoError) {
-    if (
-      isRetryableWriteError(error) ||
-      error instanceof MongoWriteConcernError ||
-      isMaxTimeMSExpiredError(error)
-    ) {
-      if (isUnknownTransactionCommitResult(error)) {
-        error.addErrorLabel(MongoErrorLabel.UnknownTransactionCommitResult);
-
-        // per txns spec, must unpin session in this case
-        session.unpin({ error });
-      }
-    } else if (error.hasErrorLabel(MongoErrorLabel.TransientTransactionError)) {
-      session.unpin({ error });
-    }
-  }
-
-  throw error;
-}
-
 /** @public */
 export type ServerSessionId = { id: Binary };