diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1fb39b70cf..1d4cc8973a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,8 @@ N/A
 
 - [#1669](https://github.com/oauth2-proxy/oauth2-proxy/pull/1699) Fix method deprecated error in lint (@t-katsumura)
 
+- [#1701](https://github.com/oauth2-proxy/oauth2-proxy/pull/1701) Watch the htpasswd file for changes and update the htpasswdMap (@aiciobanu)
+
 - [#1709](https://github.com/oauth2-proxy/oauth2-proxy/pull/1709) Show an alert message when basic auth credentials are invalid (@aiciobanu)
 - [#1723](https://github.com/oauth2-proxy/oauth2-proxy/pull/1723) Added ability to specify allowed TLS cipher suites. (@crbednarz)
 
diff --git a/oauthproxy.go b/oauthproxy.go
index fd13627156..c2c25a8c97 100644
--- a/oauthproxy.go
+++ b/oauthproxy.go
@@ -113,7 +113,7 @@ func NewOAuthProxy(opts *options.Options, validator func(string) bool) (*OAuthPr
 		var err error
 		basicAuthValidator, err = basic.NewHTPasswdValidator(opts.HtpasswdFile)
 		if err != nil {
-			return nil, fmt.Errorf("could not load htpasswdfile: %v", err)
+			return nil, fmt.Errorf("could not validate htpasswd: %v", err)
 		}
 	}
 
diff --git a/pkg/authentication/basic/htpasswd.go b/pkg/authentication/basic/htpasswd.go
index 47a1dd3f14..8a4ac2106c 100644
--- a/pkg/authentication/basic/htpasswd.go
+++ b/pkg/authentication/basic/htpasswd.go
@@ -8,8 +8,10 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sync"
 
 	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/logger"
+	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/watcher"
 	"golang.org/x/crypto/bcrypt"
 )
 
@@ -17,6 +19,7 @@ import (
 // Passwords must be generated with -B for bcrypt or -s for SHA1.
 type htpasswdMap struct {
 	users map[string]interface{}
+	rwm   sync.RWMutex
 }
 
 // bcryptPass is used to identify bcrypt passwords in the
@@ -30,10 +33,30 @@ type sha1Pass string
 // NewHTPasswdValidator constructs an httpasswd based validator from the file
 // at the path given.
 func NewHTPasswdValidator(path string) (Validator, error) {
+	h := &htpasswdMap{users: make(map[string]interface{})}
+
+	if err := h.loadHTPasswdFile(path); err != nil {
+		return nil, fmt.Errorf("could not load htpasswd file: %v", err)
+	}
+
+	if err := watcher.WatchFileForUpdates(path, nil, func() {
+		err := h.loadHTPasswdFile(path)
+		if err != nil {
+			logger.Errorf("%v: no changes were made to the current htpasswd map", err)
+		}
+	}); err != nil {
+		return nil, fmt.Errorf("could not watch htpasswd file: %v", err)
+	}
+
+	return h, nil
+}
+
+// loadHTPasswdFile loads htpasswd entries from an io.Reader (an opened file) into a htpasswdMap.
+func (h *htpasswdMap) loadHTPasswdFile(filename string) error {
 	// We allow HTPasswd location via config options
-	r, err := os.Open(path) // #nosec G304
+	r, err := os.Open(filename) // #nosec G304
 	if err != nil {
-		return nil, fmt.Errorf("could not open htpasswd file: %v", err)
+		return fmt.Errorf("could not open htpasswd file: %v", err)
 	}
 	defer func(c io.Closer) {
 		cerr := c.Close()
@@ -41,48 +64,81 @@ func NewHTPasswdValidator(path string) (Validator, error) {
 			logger.Fatalf("error closing the htpasswd file: %v", cerr)
 		}
 	}(r)
-	return newHtpasswd(r)
-}
 
-// newHtpasswd consctructs an htpasswd from an io.Reader (an opened file).
-func newHtpasswd(file io.Reader) (*htpasswdMap, error) {
-	csvReader := csv.NewReader(file)
+	csvReader := csv.NewReader(r)
 	csvReader.Comma = ':'
 	csvReader.Comment = '#'
 	csvReader.TrimLeadingSpace = true
 
 	records, err := csvReader.ReadAll()
 	if err != nil {
-		return nil, fmt.Errorf("could not read htpasswd file: %v", err)
+		return fmt.Errorf("could not read htpasswd file: %v", err)
 	}
 
-	return createHtpasswdMap(records)
+	updated, err := createHtpasswdMap(records)
+	if err != nil {
+		return fmt.Errorf("htpasswd entries error: %v", err)
+	}
+
+	h.rwm.Lock()
+	h.users = updated.users
+	h.rwm.Unlock()
+
+	return nil
 }
 
 // createHtasswdMap constructs an htpasswdMap from the given records
 func createHtpasswdMap(records [][]string) (*htpasswdMap, error) {
 	h := &htpasswdMap{users: make(map[string]interface{})}
+	var invalidRecords, invalidEntries []string
 	for _, record := range records {
-		user, realPassword := record[0], record[1]
-		shaPrefix := realPassword[:5]
-		if shaPrefix == "{SHA}" {
-			h.users[user] = sha1Pass(realPassword[5:])
-			continue
+		// If a record is invalid or malformed don't panic with index out of range,
+		// return a formatted error.
+		lr := len(record)
+		switch {
+		case lr == 2:
+			user, realPassword := record[0], record[1]
+			invalidEntries = passShaOrBcrypt(h, user, realPassword)
+		case lr == 1, lr > 2:
+			invalidRecords = append(invalidRecords, record[0])
 		}
+	}
 
-		bcryptPrefix := realPassword[:4]
-		if bcryptPrefix == "$2a$" || bcryptPrefix == "$2b$" || bcryptPrefix == "$2x$" || bcryptPrefix == "$2y$" {
-			h.users[user] = bcryptPass(realPassword)
-			continue
-		}
+	if len(invalidRecords) > 0 {
+		return h, fmt.Errorf("invalid htpasswd record(s) %+q", invalidRecords)
+	}
+
+	if len(invalidEntries) > 0 {
+		return h, fmt.Errorf("'%+q' user(s) could not be added: invalid password, must be a SHA or bcrypt entry", invalidEntries)
+	}
 
-		// Password is neither sha1 or bcrypt
-		// TODO(JoelSpeed): In the next breaking release, make this return an error.
-		logger.Errorf("Invalid htpasswd entry for %s. Must be a SHA or bcrypt entry.", user)
+	if len(h.users) == 0 {
+		return nil, fmt.Errorf("could not construct htpasswdMap: htpasswd file doesn't contain a single valid user entry")
 	}
+
 	return h, nil
 }
 
+// passShaOrBcrypt checks if a htpasswd entry is valid and the password is encrypted with SHA or bcrypt.
+// Valid user entries are saved in the htpasswdMap, invalid records are reurned.
+func passShaOrBcrypt(h *htpasswdMap, user, password string) (invalidEntries []string) {
+	passLen := len(password)
+	switch {
+	case passLen > 6 && password[:5] == "{SHA}":
+		h.users[user] = sha1Pass(password[5:])
+	case passLen > 5 &&
+		(password[:4] == "$2b$" ||
+			password[:4] == "$2y$" ||
+			password[:4] == "$2x$" ||
+			password[:4] == "$2a$"):
+		h.users[user] = bcryptPass(password)
+	default:
+		invalidEntries = append(invalidEntries, user)
+	}
+
+	return invalidEntries
+}
+
 // Validate checks a users password against the htpasswd entries
 func (h *htpasswdMap) Validate(user string, password string) bool {
 	realPassword, exists := h.users[user]
diff --git a/pkg/authentication/basic/htpasswd_test.go b/pkg/authentication/basic/htpasswd_test.go
index 0c2a197e56..d5b4150f18 100644
--- a/pkg/authentication/basic/htpasswd_test.go
+++ b/pkg/authentication/basic/htpasswd_test.go
@@ -1,8 +1,11 @@
 package basic
 
 import (
+	"os"
+
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
+	. "github.com/onsi/gomega/types"
 )
 
 const (
@@ -84,13 +87,89 @@ var _ = Describe("HTPasswd Suite", func() {
 				})
 
 				It("returns an error", func() {
-					Expect(err).To(MatchError("could not open htpasswd file: open ./test/htpasswd-doesnt-exist.txt: no such file or directory"))
+					Expect(err).To(MatchError("could not load htpasswd file: could not open htpasswd file: open ./test/htpasswd-doesnt-exist.txt: no such file or directory"))
 				})
 
 				It("returns a nil validator", func() {
 					Expect(validator).To(BeNil())
 				})
 			})
+
+			Context("htpasswd file is updated", func() {
+				const filePathPrefix = "htpasswd-file-updated-"
+				const adminUserHtpasswdEntry = "admin:$2y$05$SXWrNM7ldtbRzBvUC3VXyOvUeiUcP45XPwM93P5eeGOEPIiAZmJjC"
+				const user1HtpasswdEntry = "user1:$2y$05$/sZYJOk8.3Etg4V6fV7puuXfCJLmV5Q7u3xvKpjBSJUka.t2YtmmG"
+				var fileNames []string
+
+				AfterSuite(func() {
+					for _, v := range fileNames {
+						err := os.Remove(v)
+						Expect(err).ToNot(HaveOccurred())
+					}
+
+				})
+
+				type htpasswdUpdate struct {
+					testText              string
+					remove                bool
+					expectedLen           int
+					expectedGomegaMatcher GomegaMatcher
+				}
+
+				assertHtpasswdMapUpdate := func(hu htpasswdUpdate) {
+					var validator Validator
+					var file *os.File
+					var err error
+
+					// Create a temporary file with at least one entry
+					file, err = os.CreateTemp("", filePathPrefix)
+					Expect(err).ToNot(HaveOccurred())
+					_, err = file.WriteString(adminUserHtpasswdEntry + "\n")
+					Expect(err).ToNot(HaveOccurred())
+
+					validator, err = NewHTPasswdValidator(file.Name())
+					Expect(err).ToNot(HaveOccurred())
+
+					htpasswd, ok := validator.(*htpasswdMap)
+					Expect(ok).To(BeTrue())
+
+					if hu.remove {
+						// Overwrite the original file with another entry
+						err = os.WriteFile(file.Name(), []byte(user1HtpasswdEntry+"\n"), 0644)
+						Expect(err).ToNot(HaveOccurred())
+					} else {
+						// Add another entry to the original file in append mode
+						_, err = file.WriteString(user1HtpasswdEntry + "\n")
+						Expect(err).ToNot(HaveOccurred())
+					}
+
+					err = file.Close()
+					Expect(err).ToNot(HaveOccurred())
+
+					fileNames = append(fileNames, file.Name())
+
+					It("has the correct number of users", func() {
+						Expect(len(htpasswd.users)).To(Equal(hu.expectedLen))
+					})
+
+					It(hu.testText, func() {
+						Expect(htpasswd.Validate(adminUser, adminPassword)).To(hu.expectedGomegaMatcher)
+					})
+
+					It("new entry is present", func() {
+						Expect(htpasswd.Validate(user1, user1Password)).To(BeTrue())
+					})
+				}
+
+				Context("htpasswd entry is added", func() {
+					assertHtpasswdMapUpdate(htpasswdUpdate{"initial entry is present", false, 2, BeTrue()})
+				})
+
+				Context("htpasswd entry is removed", func() {
+					assertHtpasswdMapUpdate(htpasswdUpdate{"initial entry is removed", true, 1, BeFalse()})
+				})
+
+			})
 		})
 	})
 })
diff --git a/pkg/watcher/watcher.go b/pkg/watcher/watcher.go
new file mode 100644
index 0000000000..6a8a60d586
--- /dev/null
+++ b/pkg/watcher/watcher.go
@@ -0,0 +1,81 @@
+package watcher
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/fsnotify/fsnotify"
+
+	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/logger"
+)
+
+// WatchFileForUpdates performs an action every time a file on disk is updated
+func WatchFileForUpdates(filename string, done <-chan bool, action func()) error {
+	filename = filepath.Clean(filename)
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		return fmt.Errorf("failed to create watcher for '%s': %s", filename, err)
+	}
+
+	go func() {
+		defer watcher.Close()
+
+		for {
+			select {
+			case <-done:
+				logger.Printf("shutting down watcher for: %s", filename)
+				return
+			case event := <-watcher.Events:
+				filterEvent(watcher, event, filename, action)
+			case err = <-watcher.Errors:
+				logger.Errorf("error watching '%s': %s", filename, err)
+			}
+		}
+	}()
+	if err := watcher.Add(filename); err != nil {
+		return fmt.Errorf("failed to add '%s' to watcher: %v", filename, err)
+	}
+	logger.Printf("watching '%s' for updates", filename)
+
+	return nil
+}
+
+// Filter file operations based on the events sent by the watcher.
+// Execute the action() function when the following conditions are met:
+//  - the real path of the file was changed (Kubernetes ConfigMap/Secret)
+//  - the file is modified or created
+func filterEvent(watcher *fsnotify.Watcher, event fsnotify.Event, filename string, action func()) {
+	switch filepath.Clean(event.Name) == filename {
+	// In Kubernetes the file path is a symlink, so we should take action
+	// when the ConfigMap/Secret is replaced.
+	case event.Op&fsnotify.Remove != 0:
+		logger.Printf("watching interrupted on event: %s", event)
+		WaitForReplacement(filename, event.Op, watcher)
+		action()
+	case event.Op&(fsnotify.Create|fsnotify.Write) != 0:
+		logger.Printf("reloading after event: %s", event)
+		action()
+	}
+}
+
+// WaitForReplacement waits for a file to exist on disk and then starts a watch
+// for the file
+func WaitForReplacement(filename string, op fsnotify.Op, watcher *fsnotify.Watcher) {
+	const sleepInterval = 50 * time.Millisecond
+
+	// Avoid a race when fsnofity.Remove is preceded by fsnotify.Chmod.
+	if op&fsnotify.Chmod != 0 {
+		time.Sleep(sleepInterval)
+	}
+	for {
+		if _, err := os.Stat(filename); err == nil {
+			if err := watcher.Add(filename); err == nil {
+				logger.Printf("watching resumed for '%s'", filename)
+				return
+			}
+		}
+		time.Sleep(sleepInterval)
+	}
+}
diff --git a/validator.go b/validator.go
index 7f5349a81d..587ef857fe 100644
--- a/validator.go
+++ b/validator.go
@@ -9,6 +9,7 @@ import (
 	"unsafe"
 
 	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/logger"
+	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/watcher"
 )
 
 // UserMap holds information from the authenticated emails file
@@ -26,7 +27,7 @@ func NewUserMap(usersFile string, done <-chan bool, onUpdate func()) *UserMap {
 	atomic.StorePointer(&um.m, unsafe.Pointer(&m)) // #nosec G103
 	if usersFile != "" {
 		logger.Printf("using authenticated emails file %s", usersFile)
-		WatchForUpdates(usersFile, done, func() {
+		watcher.WatchFileForUpdates(usersFile, done, func() {
 			um.LoadAuthenticatedEmailsFile()
 			onUpdate()
 		})
diff --git a/watcher.go b/watcher.go
deleted file mode 100644
index 86c3e6532e..0000000000
--- a/watcher.go
+++ /dev/null
@@ -1,81 +0,0 @@
-//go:build go1.3 && !plan9 && !solaris
-// +build go1.3,!plan9,!solaris
-
-package main
-
-import (
-	"os"
-	"path/filepath"
-	"time"
-
-	"github.com/fsnotify/fsnotify"
-
-	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/logger"
-)
-
-// WaitForReplacement waits for a file to exist on disk and then starts a watch
-// for the file
-func WaitForReplacement(filename string, op fsnotify.Op,
-	watcher *fsnotify.Watcher) {
-	const sleepInterval = 50 * time.Millisecond
-
-	// Avoid a race when fsnofity.Remove is preceded by fsnotify.Chmod.
-	if op&fsnotify.Chmod != 0 {
-		time.Sleep(sleepInterval)
-	}
-	for {
-		if _, err := os.Stat(filename); err == nil {
-			if err := watcher.Add(filename); err == nil {
-				logger.Printf("watching resumed for %s", filename)
-				return
-			}
-		}
-		time.Sleep(sleepInterval)
-	}
-}
-
-// WatchForUpdates performs an action every time a file on disk is updated
-func WatchForUpdates(filename string, done <-chan bool, action func()) {
-	filename = filepath.Clean(filename)
-	watcher, err := fsnotify.NewWatcher()
-	if err != nil {
-		logger.Fatal("failed to create watcher for ", filename, ": ", err)
-	}
-	go func() {
-		defer func(w *fsnotify.Watcher) {
-			cerr := w.Close()
-			if cerr != nil {
-				logger.Fatalf("error closing watcher: %v", err)
-			}
-		}(watcher)
-		for {
-			select {
-			case <-done:
-				logger.Printf("Shutting down watcher for: %s", filename)
-				return
-			case event := <-watcher.Events:
-				// On Arch Linux, it appears Chmod events precede Remove events,
-				// which causes a race between action() and the coming Remove event.
-				// If the Remove wins, the action() (which calls
-				// UserMap.LoadAuthenticatedEmailsFile()) crashes when the file
-				// can't be opened.
-				if event.Op&(fsnotify.Remove|fsnotify.Rename|fsnotify.Chmod) != 0 {
-					logger.Printf("watching interrupted on event: %s", event)
-					err = watcher.Remove(filename)
-					if err != nil {
-						logger.Printf("error removing watcher on %s: %v", filename, err)
-					}
-					WaitForReplacement(filename, event.Op, watcher)
-				}
-				logger.Printf("reloading after event: %s", event)
-				action()
-			case err = <-watcher.Errors:
-				logger.Errorf("error watching %s: %s", filename, err)
-			}
-		}
-	}()
-	if err = watcher.Add(filename); err != nil {
-		logger.Fatal("failed to add ", filename, " to watcher: ", err)
-	}
-	logger.Printf("watching %s for updates", filename)
-}
diff --git a/watcher_unsupported.go b/watcher_unsupported.go
deleted file mode 100644
index 0f9e5f67d6..0000000000
--- a/watcher_unsupported.go
+++ /dev/null
@@ -1,11 +0,0 @@
-//go:build !go1.3 || plan9 || solaris
-// +build !go1.3 plan9 solaris
-
-package main
-
-import "github.com/oauth2-proxy/oauth2-proxy/v7/pkg/logger"
-
-func WatchForUpdates(filename string, done <-chan bool, action func()) {
-	logger.Errorf("file watching not implemented on this platform")
-	go func() { <-done }()
-}