diff --git a/toolkit/components/search/tests/xpcshell/test_engine_selector_variants.js b/toolkit/components/search/tests/xpcshell/test_engine_selector_variants.js
new file mode 100644
index 000000000000..0fd57f2094d1
--- /dev/null
+++ b/toolkit/components/search/tests/xpcshell/test_engine_selector_variants.js
@@ -0,0 +1,203 @@
+/* Any copyright is dedicated to the Public Domain.
+http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * This tests the SearchEngineSelector matching the correct variant engine.
+ * If multiple variants match, it should add the matching variants to the base
+ * cumulatively.
+ */
+
+"use strict";
+
+const CONFIG = [
+  {
+    recordType: "engine",
+    identifier: "engine-1",
+    base: {},
+    urls: {
+      search: {
+        params: [
+          {
+            name: "partner-code",
+            value: "code",
+          },
+        ],
+      },
+    },
+    variants: [
+      {
+        environment: { regions: ["CA", "GB", "IT"] },
+        urls: {
+          search: {
+            params: [],
+          },
+        },
+      },
+      {
+        environment: { regions: ["CA", "US"] },
+        urls: {
+          search: {
+            params: [
+              {
+                name: "partner-code",
+                value: "bar",
+              },
+            ],
+          },
+        },
+        telemetrySuffix: "telemetry",
+      },
+      {
+        environment: { regions: ["CA", "GB"] },
+        urls: {
+          search: {
+            params: [
+              {
+                name: "partner-code",
+                value: "foo",
+              },
+            ],
+          },
+        },
+        searchTermParamName: "search-param",
+      },
+    ],
+  },
+  {
+    recordType: "defaultEngines",
+    specificDefaults: [],
+  },
+  {
+    recordType: "engineOrders",
+    orders: [],
+  },
+];
+
+const CONFIG_CLONE = structuredClone(CONFIG);
+
+const engineSelector = new SearchEngineSelector();
+let settings;
+let configStub;
+
+/**
+ * This function asserts if the actual engines returned equals the expected
+ * engines.
+ *
+ * @param {object} config
+ *   A fake search config containing engines.
+ * @param {object} userEnv
+ *   A fake user's environment including locale and region, experiment, etc.
+ * @param {Array} expectedEngines
+ *   The array of expected engines to be returned from the fake config.
+ * @param {string} message
+ *   The assertion message.
+ */
+async function assertActualEnginesEqualsExpected(
+  config,
+  userEnv,
+  expectedEngines,
+  message
+) {
+  engineSelector._configuration = null;
+  configStub.returns(config);
+  let { engines } = await engineSelector.fetchEngineConfiguration(userEnv);
+
+  Assert.deepEqual(engines, expectedEngines, message);
+}
+
+add_setup(async function () {
+  settings = await RemoteSettings(SearchUtils.NEW_SETTINGS_KEY);
+  configStub = sinon.stub(settings, "get");
+});
+
+add_task(async function test_no_variants_match() {
+  await assertActualEnginesEqualsExpected(
+    CONFIG,
+    {
+      locale: "fi",
+      region: "FI",
+    },
+    [],
+    "Should match no variants."
+  );
+});
+
+add_task(async function test_match_and_apply_all_variants() {
+  await assertActualEnginesEqualsExpected(
+    CONFIG,
+    {
+      locale: "en-US",
+      region: "CA",
+    },
+    [
+      {
+        identifier: "engine-1",
+        urls: { search: { params: [{ name: "partner-code", value: "foo" }] } },
+        telemetrySuffix: "telemetry",
+        searchTermParamName: "search-param",
+      },
+    ],
+    "Should match all variants and apply each variant property cumulatively."
+  );
+});
+
+add_task(async function test_match_middle_variant() {
+  await assertActualEnginesEqualsExpected(
+    CONFIG,
+    {
+      locale: "en-US",
+      region: "US",
+    },
+    [
+      {
+        identifier: "engine-1",
+        urls: { search: { params: [{ name: "partner-code", value: "bar" }] } },
+        telemetrySuffix: "telemetry",
+      },
+    ],
+    "Should match first and second variants."
+  );
+});
+
+add_task(async function test_match_first_and_last_variant() {
+  await assertActualEnginesEqualsExpected(
+    CONFIG,
+    {
+      locale: "en-GB",
+      region: "GB",
+    },
+    [
+      {
+        identifier: "engine-1",
+        urls: { search: { params: [{ name: "partner-code", value: "foo" }] } },
+        searchTermParamName: "search-param",
+      },
+    ],
+    "Should match first and last variant."
+  );
+});
+
+add_task(async function test_match_variant_with_empty_params() {
+  await assertActualEnginesEqualsExpected(
+    CONFIG,
+    {
+      locale: "it",
+      region: "IT",
+    },
+    [
+      {
+        identifier: "engine-1",
+        urls: { search: { params: [] } },
+      },
+    ],
+    "Should match the first variant with empty params."
+  );
+});
+
+add_task(async function test_config_has_not_been_modified() {
+  Assert.deepEqual(
+    CONFIG,
+    CONFIG_CLONE,
+    "Should not modify the original test config after applying variant engines to the base engine."
+  );
+});
diff --git a/toolkit/components/search/tests/xpcshell/xpcshell.toml b/toolkit/components/search/tests/xpcshell/xpcshell.toml
index 54d8b07e4293..e6f5e11ef4a2 100644
--- a/toolkit/components/search/tests/xpcshell/xpcshell.toml
+++ b/toolkit/components/search/tests/xpcshell/xpcshell.toml
@@ -121,6 +121,8 @@ tags = "remotesettings searchmain"
 
 ["test_engine_selector_remote_override.js"]
 
+["test_engine_selector_variants.js"]
+
 ["test_engine_set_alias.js"]
 
 ["test_getSubmission_encoding.js"]