diff --git a/NEWS.md b/NEWS.md
index e6e5d30469..07073e65b6 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -5,6 +5,7 @@
 * `infix_spaces_linter()` distinguishes `<-`, `:=`, `<<-` and `->`, `->>`, i.e. `infix_spaces_linter(exclude_operators = "->")` will no longer exclude `->>` (#2115, @MichaelChirico). This change is breaking for users relying on manually-supplied `exclude_operators` containing `"<-"` to also exclude `:=` and `<<-`. The fix is to manually supply `":="` and `"<<-"` as well. We don't expect this change to affect many users, the fix is simple, and the new behavior is much more transparent, so we are including this breakage in a minor release.
 * Removed `find_line()` and `find_column()` entries from `get_source_expressions()` expression-level objects. These have been marked deprecated since version 3.0.0. No users were found on GitHub.
 * There is experimental support for writing config in plain R scripts (as opposed to DCF files; #1210, @MichaelChirico). The script is run in a new environment and variables matching settings (`?default_settings`) are copied over. In particular, this removes the need to write R code in a DCF-friendly way, and allows normal R syntax highlighting in the saved file. We may eventually deprecate the DCF approach in favor of this one; user feedback is welcome on strong preferences for either approach, or for a different approach like YAML. Generally you should be able to convert your existing `.lintr` file to an equivalent R config by replacing the `:` key-value separators with assignments (`<-`). By default, such a config is searched for in a file named '.lintr.R'. This is a mildly breaking change if you happened to be keeping a file '.lintr.R' around since that file is given precedence over '.lintr'.
+  + We also validate config files up-front make it clearer when invalid configs are present (#2195, @MichaelChirico). There is a warning for "invalid" settings, i.e., settings not part of `?default_settings`. We think this is more likely to affect users declaring settings in R, since any variable defined in the config that's not a setting must be removed to make it clearer which variables are settings vs. ancillary.
 
 ## Bug fixes
 
diff --git a/R/exclude.R b/R/exclude.R
index ae5901f1d1..d43348a403 100644
--- a/R/exclude.R
+++ b/R/exclude.R
@@ -10,18 +10,25 @@
 #'   "@details",
 #'   "Exclusions can be specified in three different ways.",
 #'   "",
-#'   "1. single line in the source file. default: `# nolint`, possibly followed by a listing of linters to exclude.",
+#'   "1. Single line in the source file. default: `# nolint`, possibly followed by a listing of linters to exclude.",
 #'   "   If the listing is missing, all linters are excluded on that line. The default listing format is",
 #'   paste(
 #'     "   `#",
 #'     "nolint: linter_name, linter2_name.`. There may not be anything between the colon and the line exclusion tag"
 #'   ),
 #'   "   and the listing must be terminated with a full stop (`.`) for the linter list to be respected.",
-#'   "2. line range in the source file. default: `# nolint start`, `# nolint end`. `# nolint start` accepts linter",
+#'   "2. Line range in the source file. default: `# nolint start`, `# nolint end`. `# nolint start` accepts linter",
 #'   "   lists in the same form as `# nolint`.",
-#'   "3. exclusions parameter, a named list of files with named lists of linters and lines to exclude them on, a named",
-#'   "   list of the files and lines to exclude, or just the filenames if you want to exclude the entire file, or the",
-#'   "   directory names if you want to exclude all files in a directory."
+#'   "3. Exclusions parameter, a list with named and/or unnamed entries. ",
+#'   "   Outer elements have the following characteristics:",
+#'   "   1. Unnamed elements specify filenames or directories.",
+#'   "   2. Named elements are a vector or list of line numbers, with `Inf` indicating 'all lines'.",
+#'   "      The name gives a path relative to the config.",
+#'   "      1. Unnamed elements denote exclusion of all linters in the given path or directory.",
+#'   "      2. Named elements, where the name specifies a linter, denote exclusion for that linter.",
+#'   "   For convenience, a vector can be used in place of a list whenever it would not introduce ambiguity, e.g.",
+#'   "   a character vector of files to exclude or a vector of lines to exclude.",
+#'   NULL
 #' )
 exclude <- function(lints, exclusions = settings$exclusions, linter_names = NULL, ...) {
   if (length(lints) <= 0L) {
diff --git a/R/settings.R b/R/settings.R
index 8addc45e7e..3aed607135 100644
--- a/R/settings.R
+++ b/R/settings.R
@@ -32,6 +32,7 @@ read_settings <- function(filename) {
   }
 
   config <- read_config_file(config_file)
+  validate_config_file(config, config_file, default_settings)
 
   for (setting in names(default_settings)) {
     value <- get_setting(setting, config, default_settings)
@@ -77,6 +78,97 @@ read_config_file <- function(config_file) {
   config
 }
 
+validate_config_file <- function(config, config_file, defaults) {
+  matched <- names(config) %in% names(defaults)
+  if (!all(matched)) {
+    warning("Found unused settings in config '", config_file, "': ", toString(names(config)[!matched]))
+  }
+
+  validate_regex(config,
+    c("exclude", "exclude_next", "exclude_start", "exclude_end", "exclude_linter", "exclude_linter_sep")
+  )
+  validate_character_string(config, c("encoding", "cache_directory", "comment_token"))
+  validate_true_false(config, c("comment_bot", "error_on_lint"))
+  validate_linters(config$linters)
+  validate_exclusions(config$exclusions)
+}
+
+is_character_string <- function(x) is.character(x) && length(x) == 1L && !is.na(x)
+is_valid_regex <- function(str) !inherits(tryCatch(grepl(str, ""), condition = identity), "condition")
+is_single_regex <- function(x) is_character_string(x) && is_valid_regex(x)
+is_true_false <- function(x) is.logical(x) && length(x) == 1L && !is.na(x)
+
+validate_keys <- function(config, keys, test, what) {
+  for (key in keys) {
+    val <- config[[key]]
+    if (is.null(val)) {
+      next
+    }
+    if (!test(val)) {
+      stop("Setting '", key, "' should be ", what, ", not '", toString(val), "'.")
+    }
+  }
+}
+
+validate_regex <- function(config, keys) {
+  validate_keys(config, keys, is_single_regex, "a single regular expression")
+}
+
+validate_character_string <- function(config, keys) {
+  validate_keys(config, keys, is_character_string, "a character string")
+}
+
+validate_true_false <- function(config, keys) {
+  validate_keys(config, keys, is_true_false, "TRUE or FALSE")
+}
+
+validate_linters <- function(linters) {
+  if (is.null(linters)) {
+    return(invisible())
+  }
+
+  is_linters <- vapply(linters, is_linter, logical(1L))
+  if (!all(is_linters)) {
+    stop(
+      "Setting 'linters' should be a list of linters, but found non-linters at elements ",
+      toString(which(!is_linters)), "."
+    )
+  }
+}
+
+validate_exclusions <- function(exclusions) {
+  if (is.null(exclusions)) {
+    return(invisible())
+  }
+
+  exclusion_names <- names2(exclusions)
+  has_names <- exclusion_names != ""
+  unnamed_is_string <-
+    vapply(exclusions[!has_names], function(x) is.character(x) && length(x) == 1L && !is.na(x), logical(1L))
+  if (!all(unnamed_is_string)) {
+    stop(
+      "Unnamed entries of setting 'exclusions' should be strings naming files or directories, check entries: ",
+      toString(which(!has_names)[!unnamed_is_string]), "."
+    )
+  }
+  for (ii in which(has_names)) validate_named_exclusion(exclusions, ii)
+}
+
+validate_named_exclusion <- function(exclusions, idx) {
+  entry <- exclusions[[idx]]
+  if (is.list(entry)) {
+    valid_entry <- vapply(entry, function(x) is.numeric(x) && !anyNA(x), logical(1L))
+  } else {
+    valid_entry <- is.numeric(entry) && !anyNA(entry)
+  }
+  if (!all(valid_entry)) {
+    stop(
+      "Named entries of setting 'exclusions' should designate line numbers for exclusion, ",
+      "check exclusion: ", idx, "."
+    )
+  }
+}
+
 lintr_option <- function(setting, default = NULL) getOption(paste0("lintr.", setting), default)
 
 get_setting <- function(setting, config, defaults) {
diff --git a/R/zzz.R b/R/zzz.R
index b9d6f4b7c2..226063c9b0 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -250,7 +250,7 @@ default_undesirable_operators <- all_undesirable_operators[names(all_undesirable
 #'  - `exclude`: pattern used to exclude a line of code
 #'  - `exclude_start`, `exclude_end`: patterns used to mark start and end of the code block to exclude
 #'  - `exclude_linter`, `exclude_linter_sep`: patterns used to exclude linters
-#'  - `exclusions`:a list of files to exclude
+#'  - `exclusions`: a list of exclusions, see [exclude()] for a complete description of valid values.
 #'  - `cache_directory`: location of cache directory
 #'  - `comment_token`: a GitHub token character
 #'  - `comment_bot`: decides if lintr comment bot on GitHub can comment on commits
diff --git a/man/default_settings.Rd b/man/default_settings.Rd
index 11c92cb35d..d002398168 100644
--- a/man/default_settings.Rd
+++ b/man/default_settings.Rd
@@ -23,7 +23,7 @@ The default settings consist of
 \item \code{exclude}: pattern used to exclude a line of code
 \item \code{exclude_start}, \code{exclude_end}: patterns used to mark start and end of the code block to exclude
 \item \code{exclude_linter}, \code{exclude_linter_sep}: patterns used to exclude linters
-\item \code{exclusions}:a list of files to exclude
+\item \code{exclusions}: a list of exclusions, see \code{\link[=exclude]{exclude()}} for a complete description of valid values.
 \item \code{cache_directory}: location of cache directory
 \item \code{comment_token}: a GitHub token character
 \item \code{comment_bot}: decides if lintr comment bot on GitHub can comment on commits
diff --git a/man/exclude.Rd b/man/exclude.Rd
index 17ccdaba2d..3a97087e19 100644
--- a/man/exclude.Rd
+++ b/man/exclude.Rd
@@ -21,14 +21,24 @@ Exclude lines or files from linting
 \details{
 Exclusions can be specified in three different ways.
 \enumerate{
-\item single line in the source file. default: \verb{# nolint}, possibly followed by a listing of linters to exclude.
+\item Single line in the source file. default: \verb{# nolint}, possibly followed by a listing of linters to exclude.
 If the listing is missing, all linters are excluded on that line. The default listing format is
 \verb{# nolint: linter_name, linter2_name.}. There may not be anything between the colon and the line exclusion tag
 and the listing must be terminated with a full stop (\code{.}) for the linter list to be respected.
-\item line range in the source file. default: \verb{# nolint start}, \verb{# nolint end}. \verb{# nolint start} accepts linter
+\item Line range in the source file. default: \verb{# nolint start}, \verb{# nolint end}. \verb{# nolint start} accepts linter
 lists in the same form as \verb{# nolint}.
-\item exclusions parameter, a named list of files with named lists of linters and lines to exclude them on, a named
-list of the files and lines to exclude, or just the filenames if you want to exclude the entire file, or the
-directory names if you want to exclude all files in a directory.
+\item Exclusions parameter, a list with named and/or unnamed entries.
+Outer elements have the following characteristics:
+\enumerate{
+\item Unnamed elements specify filenames or directories.
+\item Named elements are a vector or list of line numbers, with \code{Inf} indicating 'all lines'.
+The name gives a path relative to the config.
+\enumerate{
+\item Unnamed elements denote exclusion of all linters in the given path or directory.
+\item Named elements, where the name specifies a linter, denote exclusion for that linter.
+For convenience, a vector can be used in place of a list whenever it would not introduce ambiguity, e.g.
+a character vector of files to exclude or a vector of lines to exclude.
+}
+}
 }
 }
diff --git a/tests/testthat/test-lint_package.R b/tests/testthat/test-lint_package.R
index 598f2a9ffd..ae95bdde67 100644
--- a/tests/testthat/test-lint_package.R
+++ b/tests/testthat/test-lint_package.R
@@ -217,9 +217,13 @@ test_that("package using .lintr.R config lints correctly", {
 
   # config produces unused variables
   withr::local_options(lintr.linter_file = "lintr_test_config_extraneous")
-  expect_length(lint_package(r_config_pkg), 2L)
+  expect_warning(
+    expect_length(lint_package(r_config_pkg), 2L),
+    "Found unused settings in config",
+    fixed = TRUE
+  )
 
-  # DCF is preferred if multiple matched configs
+  # R is preferred if multiple matched configs
   withr::local_options(lintr.linter_file = "lintr_test_config_conflict")
   lints <- as.data.frame(lint_package(r_config_pkg))
   expect_identical(unique(basename(lints$filename)), "testthat.R")
diff --git a/tests/testthat/test-settings.R b/tests/testthat/test-settings.R
index 7631be1dbf..cd9cdbabdc 100644
--- a/tests/testthat/test-settings.R
+++ b/tests/testthat/test-settings.R
@@ -152,3 +152,110 @@ test_that("it has a smart default for encodings", {
   lintr:::read_settings(pkg_file)
   expect_identical(settings$encoding, "ISO8859-1")
 })
+
+test_that("validate_config_file() detects improperly-formed settings", {
+  .lintr <- withr::local_tempfile()
+  withr::local_options(lintr.linter_file = .lintr)
+  withr::local_dir(withr::local_tempdir())
+
+  writeLines("asdf: 1", .lintr)
+  expect_warning(lint_dir(), "Found unused settings in config", fixed = TRUE)
+
+  writeLines("a=1", "aaa.R")
+  writeLines(c('exclusions: list("aaa.R")', "asdf: 1"), .lintr)
+  expect_warning(lint_dir(), "Found unused settings in config", fixed = TRUE)
+
+  writeLines("encoding: FALSE", .lintr)
+  expect_error(lint_dir(), "Setting 'encoding' should be a character string, not 'FALSE'", fixed = TRUE)
+
+  writeLines("encoding: NA_character_", .lintr)
+  expect_error(lint_dir(), "Setting 'encoding' should be a character string, not 'NA'", fixed = TRUE)
+
+  writeLines('encoding: c("a", "b")', .lintr)
+  expect_error(lint_dir(), "Setting 'encoding' should be a character string, not 'a, b'")
+
+  writeLines("exclude: FALSE", .lintr)
+  expect_error(lint_dir(), "Setting 'exclude' should be a single regular expression, not 'FALSE'", fixed = TRUE)
+
+  writeLines(c('exclusions: list("aaa.R")', "exclude: FALSE"), .lintr)
+  expect_error(lint_dir(), "Setting 'exclude' should be a single regular expression, not 'FALSE'", fixed = TRUE)
+
+  writeLines('exclude: "("', .lintr)
+  expect_error(lint_dir(), "Setting 'exclude' should be a single regular expression, not '('", fixed = TRUE)
+
+  writeLines('comment_bot: "a"', .lintr)
+  expect_error(lint_dir(), "Setting 'comment_bot' should be TRUE or FALSE, not 'a'", fixed = TRUE)
+
+  writeLines("comment_bot: NA", .lintr)
+  expect_error(lint_dir(), "Setting 'comment_bot' should be TRUE or FALSE, not 'NA'", fixed = TRUE)
+
+  writeLines("comment_bot: c(TRUE, FALSE)", .lintr)
+  expect_error(lint_dir(), "Setting 'comment_bot' should be TRUE or FALSE, not 'TRUE, FALSE'", fixed = TRUE)
+
+  writeLines("linters: list(1)", .lintr)
+  expect_error(lint_dir(), "Setting 'linters' should be a list of linters", fixed = TRUE)
+
+  writeLines("linters: list(assignment_linter(), 1)", .lintr)
+  expect_error(lint_dir(), "Setting 'linters' should be a list of linters", fixed = TRUE)
+
+  writeLines("exclusions: list(1L)", .lintr)
+  expect_error(lint_dir(), "Unnamed entries of setting 'exclusions' should be strings", fixed = TRUE)
+
+  writeLines('exclusions: list("aaa.R", 1L)', .lintr)
+  expect_error(lint_dir(), "Unnamed entries of setting 'exclusions' should be strings", fixed = TRUE)
+
+  writeLines("exclusions: list(letters)", .lintr)
+  expect_error(lint_dir(), "Unnamed entries of setting 'exclusions' should be strings", fixed = TRUE)
+
+  writeLines("exclusions: list(NA_character_)", .lintr)
+  expect_error(lint_dir(), "Unnamed entries of setting 'exclusions' should be strings", fixed = TRUE)
+
+  writeLines('exclusions: list(aaa.R = "abc")', .lintr)
+  expect_error(lint_dir(), "Named entries of setting 'exclusions' should designate line numbers", fixed = TRUE)
+
+  writeLines("exclusions: list(aaa.R = NA_integer_)", .lintr)
+  expect_error(lint_dir(), "Named entries of setting 'exclusions' should designate line numbers", fixed = TRUE)
+
+  writeLines('exclusions: list(aaa.R = list("abc"))', .lintr)
+  expect_error(lint_dir(), "Named entries of setting 'exclusions' should designate line numbers", fixed = TRUE)
+
+  writeLines("exclusions: list(aaa.R = list(NA_integer_))", .lintr)
+  expect_error(lint_dir(), "Named entries of setting 'exclusions' should designate line numbers", fixed = TRUE)
+
+  writeLines('exclusions: list(aaa.R = list(assignment_linter = "abc"))', .lintr)
+  expect_error(lint_dir(), "Named entries of setting 'exclusions' should designate line numbers", fixed = TRUE)
+
+  writeLines("exclusions: list(aaa.R = list(assignment_linter = NA_integer_))", .lintr)
+  expect_error(lint_dir(), "Named entries of setting 'exclusions' should designate line numbers", fixed = TRUE)
+})
+
+test_that("exclusions can be a character vector", {
+  withr::local_dir(withr::local_tempdir())
+  # exclusions are relative to dirname(.lintr), so must create it here
+  .lintr <- withr::local_tempfile(tmpdir = getwd())
+  withr::local_options(lintr.linter_file = .lintr)
+
+  writeLines('exclusions: "aaa.R"', .lintr)
+  writeLines("a<-1", "aaa.R")
+  writeLines("b<-1", "bbb.R")
+  expect_length(lint_dir(linters = infix_spaces_linter()), 1L)
+
+  writeLines('exclusions: c("aaa.R", "bbb.R")', .lintr)
+  expect_length(lint_dir(linters = infix_spaces_linter()), 0L)
+})
+
+test_that("lines Inf means 'all lines'", {
+  withr::local_dir(withr::local_tempdir())
+  # exclusions are relative to dirname(.lintr), so must create it here
+  .lintr <- withr::local_tempfile(tmpdir = getwd())
+  withr::local_options(lintr.linter_file = .lintr)
+
+  writeLines("exclusions: list(aaa.R = Inf)", .lintr)
+  writeLines("a<-1", "aaa.R")
+  expect_length(lint_dir(linters = infix_spaces_linter()), 0L)
+
+  writeLines("exclusions: list(aaa.R = list(infix_spaces_linter = Inf))", .lintr)
+  # exclude infix_spaces_linter, include assignment_linter()
+  writeLines("a=1", "aaa.R")
+  expect_length(lint_dir(linters = list(assignment_linter(), infix_spaces_linter())), 1L)
+})