diff --git a/security/certverifier/NSSCertDBTrustDomain.cpp b/security/certverifier/NSSCertDBTrustDomain.cpp
index 9ceb4aa0d61f..32a89caba933 100644
--- a/security/certverifier/NSSCertDBTrustDomain.cpp
+++ b/security/certverifier/NSSCertDBTrustDomain.cpp
@@ -13,6 +13,7 @@
 #include "ExtendedValidation.h"
 #include "MultiLogCTVerifier.h"
 #include "NSSErrorsService.h"
+#include "PKCS11ModuleDB.h"
 #include "PublicKeyPinningService.h"
 #include "cert.h"
 #include "cert_storage/src/cert_storage.h"
@@ -37,7 +38,6 @@
 #include "nsCRTGlue.h"
 #include "nsIObserverService.h"
 #include "nsNSSCallbacks.h"
-#include "nsNSSCertHelper.h"
 #include "nsNSSCertificate.h"
 #include "nsNSSCertificateDB.h"
 #include "nsNSSIOLayer.h"
@@ -102,7 +102,7 @@ NSSCertDBTrustDomain::NSSCertDBTrustDomain(
       mHostname(hostname),
       mCertStorage(do_GetService(NS_CERT_STORAGE_CID)),
       mOCSPStaplingStatus(CertVerifier::OCSP_STAPLING_NEVER_CHECKED),
-      mBuiltInRootsModule(SECMOD_FindModule(kRootModuleName)),
+      mBuiltInRootsModule(SECMOD_FindModule(kRootModuleName.get())),
       mOCSPFetchStatus(OCSPFetchStatus::NotFetched) {}
 
 static void FindRootsWithSubject(UniqueSECMODModule& rootsModule,
@@ -1686,6 +1686,8 @@ SECStatus InitializeNSS(const nsACString& dir, NSSDBConfig nssDbConfig,
     }
   }
 
+  CollectThirdPartyPKCS11ModuleTelemetry();
+
   return SECSuccess;
 }
 
@@ -1750,8 +1752,6 @@ bool LoadUserModuleAt(const char* moduleName, const char* libraryName,
   return true;
 }
 
-const char* kIPCClientCertsModuleName = "IPC Client Cert Module";
-
 bool LoadIPCClientCertsModule(const nsCString& dir) {
   // The IPC client certs module needs to be able to call back into gecko to be
   // able to communicate with the parent process over IPC. This is achieved by
@@ -1759,14 +1759,14 @@ bool LoadIPCClientCertsModule(const nsCString& dir) {
   // extra string parameter that will be available when C_Initialize is called
   // on IPC client certs.
   nsPrintfCString addrs("%p,%p", DoFindObjects, DoSign);
-  if (!LoadUserModuleAt(kIPCClientCertsModuleName, "ipcclientcerts", dir,
+  if (!LoadUserModuleAt(kIPCClientCertsModuleName.get(), "ipcclientcerts", dir,
                         addrs.get())) {
     return false;
   }
   RunOnShutdown(
       []() {
         UniqueSECMODModule ipcClientCertsModule(
-            SECMOD_FindModule(kIPCClientCertsModuleName));
+            SECMOD_FindModule(kIPCClientCertsModuleName.get()));
         if (ipcClientCertsModule) {
           SECMOD_UnloadUserModule(ipcClientCertsModule.get());
         }
@@ -1775,14 +1775,12 @@ bool LoadIPCClientCertsModule(const nsCString& dir) {
   return true;
 }
 
-const char* kOSClientCertsModuleName = "OS Client Cert Module";
-
 bool LoadOSClientCertsModule(const nsCString& dir) {
   nsLiteralCString params =
       StaticPrefs::security_osclientcerts_assume_rsa_pss_support()
           ? "RSA-PSS"_ns
           : ""_ns;
-  return LoadUserModuleAt(kOSClientCertsModuleName, "osclientcerts", dir,
+  return LoadUserModuleAt(kOSClientCertsModuleName.get(), "osclientcerts", dir,
                           params.get());
 }
 
@@ -1794,7 +1792,7 @@ bool LoadLoadableRoots(const nsCString& dir) {
   // "Root Certs" module allows us to load the correct one. See bug 1406396.
   int unusedModType;
   Unused << SECMOD_DeleteModule("Root Certs", &unusedModType);
-  return LoadUserModuleAt(kRootModuleName, "nssckbi", dir, nullptr);
+  return LoadUserModuleAt(kRootModuleName.get(), "nssckbi", dir, nullptr);
 }
 
 nsresult DefaultServerNicknameForCert(const CERTCertificate* cert,
diff --git a/security/certverifier/NSSCertDBTrustDomain.h b/security/certverifier/NSSCertDBTrustDomain.h
index a21908233977..294e5dbdc0f6 100644
--- a/security/certverifier/NSSCertDBTrustDomain.h
+++ b/security/certverifier/NSSCertDBTrustDomain.h
@@ -87,8 +87,6 @@ bool LoadLoadableRoots(const nsCString& dir);
  */
 bool LoadOSClientCertsModule(const nsCString& dir);
 
-extern const char* kOSClientCertsModuleName;
-
 /**
  * Loads the IPC client certs module.
  *
@@ -99,8 +97,6 @@ extern const char* kOSClientCertsModuleName;
  */
 bool LoadIPCClientCertsModule(const nsCString& dir);
 
-extern const char* kIPCClientCertsModuleName;
-
 /**
  * Unloads the loadable roots module and os client certs module, if loaded.
  */
diff --git a/security/manager/ssl/EnterpriseRoots.cpp b/security/manager/ssl/EnterpriseRoots.cpp
index 940037cfc898..49544300eaa8 100644
--- a/security/manager/ssl/EnterpriseRoots.cpp
+++ b/security/manager/ssl/EnterpriseRoots.cpp
@@ -6,6 +6,7 @@
 
 #include "EnterpriseRoots.h"
 
+#include "PKCS11ModuleDB.h"
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/IntegerPrintfMacros.h"
 #include "mozilla/Casting.h"
@@ -13,7 +14,6 @@
 #include "mozilla/Unused.h"
 #include "mozpkix/Result.h"
 #include "nsCRT.h"
-#include "nsNSSCertHelper.h"
 #include "nsThreadUtils.h"
 
 #ifdef MOZ_WIDGET_ANDROID
@@ -33,6 +33,7 @@
 extern mozilla::LazyLogModule gPIPNSSLog;
 
 using namespace mozilla;
+using namespace psm;
 
 void EnterpriseCert::CopyBytes(nsTArray<uint8_t>& dest) const {
   dest.Assign(mDER);
@@ -498,7 +499,7 @@ nsresult GatherEnterpriseCerts(nsTArray<EnterpriseCert>& certs) {
   }
 
   certs.Clear();
-  UniqueSECMODModule rootsModule(SECMOD_FindModule(kRootModuleName));
+  UniqueSECMODModule rootsModule(SECMOD_FindModule(kRootModuleName.get()));
 #ifdef XP_WIN
   GatherEnterpriseCertsWindows(certs, rootsModule);
 #endif  // XP_WIN
diff --git a/security/manager/ssl/PKCS11ModuleDB.cpp b/security/manager/ssl/PKCS11ModuleDB.cpp
index 3825abb8b2c5..f47fdb2b56dd 100644
--- a/security/manager/ssl/PKCS11ModuleDB.cpp
+++ b/security/manager/ssl/PKCS11ModuleDB.cpp
@@ -7,6 +7,7 @@
 #include "PKCS11ModuleDB.h"
 
 #include "ScopedNSSTypes.h"
+#include "mozilla/glean/GleanMetrics.h"
 #include "nsComponentManagerUtils.h"
 #include "nsIMutableArray.h"
 #include "nsNSSCertHelper.h"
@@ -33,7 +34,7 @@ static nsresult NormalizeModuleNameIn(const nsAString& moduleNameIn,
     return rv;
   }
   if (moduleNameIn.Equals(localizedRootModuleName)) {
-    moduleNameOut.Assign(kRootModuleName);
+    moduleNameOut.Assign(kRootModuleName.get());
     return NS_OK;
   }
   moduleNameOut.Assign(NS_ConvertUTF16toUTF8(moduleNameIn));
@@ -59,6 +60,8 @@ PKCS11ModuleDB::DeleteModule(const nsAString& aModuleName) {
     return NS_ERROR_FAILURE;
   }
 
+  CollectThirdPartyPKCS11ModuleTelemetry();
+
   return NS_OK;
 }
 
@@ -103,6 +106,9 @@ PKCS11ModuleDB::AddModule(const nsAString& aModuleName,
   if (srv != SECSuccess) {
     return NS_ERROR_FAILURE;
   }
+
+  CollectThirdPartyPKCS11ModuleTelemetry();
+
   return NS_OK;
 }
 
@@ -180,5 +186,32 @@ PKCS11ModuleDB::GetIsFIPSEnabled(bool* aIsFIPSEnabled) {
   return NS_OK;
 }
 
+const nsLiteralCString kBuiltInModuleNames[] = {
+    kNSSInternalModuleName,
+    kRootModuleName,
+    kOSClientCertsModuleName,
+    kIPCClientCertsModuleName,
+};
+
+void CollectThirdPartyPKCS11ModuleTelemetry() {
+  size_t thirdPartyModulesLoaded = 0;
+  AutoSECMODListReadLock lock;
+  for (SECMODModuleList* list = SECMOD_GetDefaultModuleList(); list;
+       list = list->next) {
+    bool isThirdParty = true;
+    for (const auto& builtInModuleName : kBuiltInModuleNames) {
+      if (builtInModuleName.Equals(list->module->commonName)) {
+        isThirdParty = false;
+        break;
+      }
+    }
+    if (isThirdParty) {
+      thirdPartyModulesLoaded++;
+    }
+  }
+  mozilla::glean::pkcs11::third_party_modules_loaded.Set(
+      thirdPartyModulesLoaded);
+}
+
 }  // namespace psm
 }  // namespace mozilla
diff --git a/security/manager/ssl/PKCS11ModuleDB.h b/security/manager/ssl/PKCS11ModuleDB.h
index c167afe41078..2fc0a557140b 100644
--- a/security/manager/ssl/PKCS11ModuleDB.h
+++ b/security/manager/ssl/PKCS11ModuleDB.h
@@ -7,6 +7,7 @@
 #define PKCS11ModuleDB_h
 
 #include "nsIPKCS11ModuleDB.h"
+#include "nsTLiteralString.h"
 
 namespace mozilla {
 namespace psm {
@@ -29,6 +30,13 @@ class PKCS11ModuleDB : public nsIPKCS11ModuleDB {
   virtual ~PKCS11ModuleDB() = default;
 };
 
+const nsLiteralCString kIPCClientCertsModuleName("IPC Client Cert Module");
+const nsLiteralCString kNSSInternalModuleName("NSS Internal PKCS #11 Module");
+const nsLiteralCString kOSClientCertsModuleName("OS Client Cert Module");
+const nsLiteralCString kRootModuleName("Builtin Roots Module");
+
+void CollectThirdPartyPKCS11ModuleTelemetry();
+
 }  // namespace psm
 }  // namespace mozilla
 
diff --git a/security/manager/ssl/RootCertificateTelemetryUtils.cpp b/security/manager/ssl/RootCertificateTelemetryUtils.cpp
index d6bd54d741c6..0b4c9968f947 100644
--- a/security/manager/ssl/RootCertificateTelemetryUtils.cpp
+++ b/security/manager/ssl/RootCertificateTelemetryUtils.cpp
@@ -6,12 +6,12 @@
 
 #include "RootCertificateTelemetryUtils.h"
 
+#include "PKCS11ModuleDB.h"
 #include "RootHashes.inc"  // Note: Generated by genRootCAHashes.js
 #include "ScopedNSSTypes.h"
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Logging.h"
 #include "nsINSSComponent.h"
-#include "nsNSSCertHelper.h"
 #include "nsServiceManagerUtils.h"
 #include "pk11pub.h"
 
@@ -109,7 +109,7 @@ int32_t RootCABinNumber(Span<const uint8_t> cert) {
   // because then it should have already matched our built-in list. This is
   // here as a backstop to catch situations where a built-in root was added but
   // the built-in telemetry information was not updated.
-  UniqueSECMODModule rootsModule(SECMOD_FindModule(kRootModuleName));
+  UniqueSECMODModule rootsModule(SECMOD_FindModule(kRootModuleName.get()));
   AutoSECMODListReadLock secmodLock;
   if (!rootsModule || rootsModule->slotCount != 1) {
     return ROOT_CERTIFICATE_UNKNOWN;
diff --git a/security/manager/ssl/metrics.yaml b/security/manager/ssl/metrics.yaml
index 3278d867fd81..f2a30decb167 100644
--- a/security/manager/ssl/metrics.yaml
+++ b/security/manager/ssl/metrics.yaml
@@ -246,3 +246,19 @@ verification_used_cert_from:
       - dkeeler@mozilla.com
     expires: never
     denominator_metric: tls.certificate_verifications
+
+pkcs11:
+  third_party_modules_loaded:
+    type: quantity
+    description:
+      The number of third-party PKCS#11 modules loaded.
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1905453
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1905453
+    data_sensitivity:
+      - interaction
+    notification_emails:
+      - dkeeler@mozilla.com
+    expires: never
+    unit: modules
diff --git a/security/manager/ssl/nsNSSCertHelper.cpp b/security/manager/ssl/nsNSSCertHelper.cpp
index 2a21400cb678..c0f0cb591008 100644
--- a/security/manager/ssl/nsNSSCertHelper.cpp
+++ b/security/manager/ssl/nsNSSCertHelper.cpp
@@ -26,12 +26,6 @@
 
 using namespace mozilla;
 
-// To avoid relying on localized strings in PSM, we hard-code the root module
-// name internally. When we display it to the user in the list of modules in the
-// front-end, we look up the localized value and display that instead of this.
-const char* kRootModuleName = "Builtin Roots Module";
-const size_t kRootModuleNameLen = strlen(kRootModuleName);
-
 static nsresult GetPIPNSSBundle(nsIStringBundle** pipnssBundle) {
   nsCOMPtr<nsIStringBundleService> bundleService(
       do_GetService(NS_STRINGBUNDLE_CONTRACTID));
diff --git a/security/manager/ssl/nsNSSCertHelper.h b/security/manager/ssl/nsNSSCertHelper.h
index 453e2e21eb3a..eb7aa4050bed 100644
--- a/security/manager/ssl/nsNSSCertHelper.h
+++ b/security/manager/ssl/nsNSSCertHelper.h
@@ -5,18 +5,8 @@
 #ifndef nsNSSCertHelper_h
 #define nsNSSCertHelper_h
 
-#ifndef INET6_ADDRSTRLEN
-#  define INET6_ADDRSTRLEN 46
-#endif
-
-#include "certt.h"
 #include "nsString.h"
 
-extern const char* kRootModuleName;
-extern const size_t kRootModuleNameLen;
-
-class nsIX509Cert;
-
 // If input is valid UTF-8, converts from UTF-8 to UTF-16. Otherwise,
 // converts from Latin1 to UTF-16.
 void LossyUTF8ToUTF16(const char* str, uint32_t len, /*out*/ nsAString& result);
diff --git a/security/manager/ssl/nsNSSComponent.cpp b/security/manager/ssl/nsNSSComponent.cpp
index 478901c38036..5891ae628f81 100644
--- a/security/manager/ssl/nsNSSComponent.cpp
+++ b/security/manager/ssl/nsNSSComponent.cpp
@@ -11,6 +11,7 @@
 #include "EnterpriseRoots.h"
 #include "ExtendedValidation.h"
 #include "NSSCertDBTrustDomain.h"
+#include "PKCS11ModuleDB.h"
 #include "SSLTokensCache.h"
 #include "ScopedNSSTypes.h"
 #include "SharedSSLState.h"
@@ -610,7 +611,7 @@ void AsyncLoadOrUnloadOSClientCertsModule(bool load) {
     Unused << task->Dispatch();
   } else {
     UniqueSECMODModule osClientCertsModule(
-        SECMOD_FindModule(kOSClientCertsModuleName));
+        SECMOD_FindModule(kOSClientCertsModuleName.get()));
     if (osClientCertsModule) {
       SECMOD_UnloadUserModule(osClientCertsModule.get());
     }
diff --git a/security/manager/ssl/nsNSSIOLayer.cpp b/security/manager/ssl/nsNSSIOLayer.cpp
index 57f5d3ae6ec4..001a60b8aa79 100644
--- a/security/manager/ssl/nsNSSIOLayer.cpp
+++ b/security/manager/ssl/nsNSSIOLayer.cpp
@@ -44,7 +44,6 @@
 #include "nsContentUtils.h"
 #include "nsISocketProvider.h"
 #include "nsIWebProgressListener.h"
-#include "nsNSSCertHelper.h"
 #include "nsNSSComponent.h"
 #include "nsNSSHelper.h"
 #include "nsPrintfCString.h"
diff --git a/security/manager/ssl/nsPKCS11Slot.cpp b/security/manager/ssl/nsPKCS11Slot.cpp
index 130e79033d88..88ac9bb0d708 100644
--- a/security/manager/ssl/nsPKCS11Slot.cpp
+++ b/security/manager/ssl/nsPKCS11Slot.cpp
@@ -6,6 +6,7 @@
 
 #include <string.h>
 
+#include "PKCS11ModuleDB.h"
 #include "mozilla/Casting.h"
 #include "mozilla/Logging.h"
 #include "mozilla/Telemetry.h"
@@ -20,6 +21,7 @@
 #include "secmod.h"
 
 using mozilla::LogLevel;
+using namespace mozilla::psm;
 
 extern mozilla::LazyLogModule gPIPNSSLog;
 
@@ -213,8 +215,10 @@ nsPKCS11Module::nsPKCS11Module(SECMODModule* module) {
 static nsresult NormalizeModuleNameOut(const char* moduleNameIn,
                                        nsACString& moduleNameOut) {
   // Easy case: this isn't the builtin roots module.
-  if (strnlen(moduleNameIn, kRootModuleNameLen + 1) != kRootModuleNameLen ||
-      strncmp(kRootModuleName, moduleNameIn, kRootModuleNameLen) != 0) {
+  if (strnlen(moduleNameIn, kRootModuleName.Length() + 1) !=
+          kRootModuleName.Length() ||
+      strncmp(kRootModuleName.get(), moduleNameIn, kRootModuleName.Length()) !=
+          0) {
     moduleNameOut.Assign(moduleNameIn);
     return NS_OK;
   }
diff --git a/security/manager/ssl/tests/unit/test_pkcs11_module.js b/security/manager/ssl/tests/unit/test_pkcs11_module.js
index abad2dbb5466..654788f937c3 100644
--- a/security/manager/ssl/tests/unit/test_pkcs11_module.js
+++ b/security/manager/ssl/tests/unit/test_pkcs11_module.js
@@ -13,7 +13,15 @@ const gModuleDB = Cc["@mozilla.org/security/pkcs11moduledb;1"].getService(
   Ci.nsIPKCS11ModuleDB
 );
 
-function run_test() {
+add_task(async function test_pkcs11_module() {
+  Services.fog.initializeFOG();
+
+  equal(
+    0,
+    await Glean.pkcs11.thirdPartyModulesLoaded.testGetValue(),
+    "should have no third-party modules to begin with"
+  );
+
   // Check that if we have never added the test module, that we don't find it
   // in the module list.
   checkPKCS11ModuleNotPresent("PKCS11 Test Module", "pkcs11testmodule");
@@ -23,6 +31,11 @@ function run_test() {
   libraryFile.append("pkcs11testmodule");
   libraryFile.append(ctypes.libraryName("pkcs11testmodule"));
   loadPKCS11Module(libraryFile, "PKCS11 Test Module", true);
+  equal(
+    1,
+    await Glean.pkcs11.thirdPartyModulesLoaded.testGetValue(),
+    "should have one third-party module after loading it"
+  );
   let testModule = checkPKCS11ModuleExists(
     "PKCS11 Test Module",
     "pkcs11testmodule"
@@ -50,9 +63,14 @@ function run_test() {
     Ci.nsIPKCS11ModuleDB
   );
   pkcs11ModuleDB.deleteModule("PKCS11 Test Module");
+  equal(
+    0,
+    await Glean.pkcs11.thirdPartyModulesLoaded.testGetValue(),
+    "should have no third-party modules after unloading it"
+  );
   checkPKCS11ModuleNotPresent("PKCS11 Test Module", "pkcs11testmodule");
 
   // Check miscellaneous module DB methods and attributes.
   ok(!gModuleDB.canToggleFIPS, "It should NOT be possible to toggle FIPS");
   ok(!gModuleDB.isFIPSEnabled, "FIPS should not be enabled");
-}
+});