diff --git a/packages/eslint-plugin/docs/rules/no-base-to-string.mdx b/packages/eslint-plugin/docs/rules/no-base-to-string.mdx
index 8097ca8b7f41..d1927bf69b5b 100644
--- a/packages/eslint-plugin/docs/rules/no-base-to-string.mdx
+++ b/packages/eslint-plugin/docs/rules/no-base-to-string.mdx
@@ -99,6 +99,17 @@ let text = `${value}`;
 String(/regex/);
 ```
 
+### `checkUnknown`
+
+{/* insert option description */}
+
+The following patterns are considered incorrect with the options `{ checkUnknown: true }`:
+
+```ts option='{ "checkUnknown": true }' showPlaygroundButton
+declare const x: unknown;
+String(x);
+```
+
 ## When Not To Use It
 
 If you don't mind a risk of `"[object Object]"` or incorrect type coercions in your values, then you will not need this rule.
diff --git a/packages/eslint-plugin/src/rules/no-base-to-string.ts b/packages/eslint-plugin/src/rules/no-base-to-string.ts
index 6617c8d1dea2..26eadce99839 100644
--- a/packages/eslint-plugin/src/rules/no-base-to-string.ts
+++ b/packages/eslint-plugin/src/rules/no-base-to-string.ts
@@ -21,6 +21,7 @@ enum Usefulness {
 export type Options = [
   {
     ignoredTypeNames?: string[];
+    checkUnknown?: boolean;
   },
 ];
 export type MessageIds = 'baseArrayJoin' | 'baseToString';
@@ -46,6 +47,10 @@ export default createRule<Options, MessageIds>({
         type: 'object',
         additionalProperties: false,
         properties: {
+          checkUnknown: {
+            type: 'boolean',
+            description: 'Whether to also check values of type `unknown`',
+          },
           ignoredTypeNames: {
             type: 'array',
             description:
@@ -60,6 +65,7 @@ export default createRule<Options, MessageIds>({
   },
   defaultOptions: [
     {
+      checkUnknown: false,
       ignoredTypeNames: ['Error', 'RegExp', 'URL', 'URLSearchParams'],
     },
   ],
@@ -76,6 +82,7 @@ export default createRule<Options, MessageIds>({
         type ?? services.getTypeAtLocation(node),
         new Set(),
       );
+
       if (certainty === Usefulness.Always) {
         return;
       }
@@ -213,7 +220,7 @@ export default createRule<Options, MessageIds>({
           return collectToStringCertainty(constraint, visited);
         }
         // unconstrained generic means `unknown`
-        return Usefulness.Always;
+        return option.checkUnknown ? Usefulness.Sometimes : Usefulness.Always;
       }
 
       // the Boolean type definition missing toString()
@@ -251,8 +258,13 @@ export default createRule<Options, MessageIds>({
       const toString =
         checker.getPropertyOfType(type, 'toString') ??
         checker.getPropertyOfType(type, 'toLocaleString');
+
       if (!toString) {
-        // e.g. any/unknown
+        // unknown
+        if (option.checkUnknown && type.flags === ts.TypeFlags.Unknown) {
+          return Usefulness.Sometimes;
+        }
+        // e.g. any
         return Usefulness.Always;
       }
 
diff --git a/packages/eslint-plugin/tests/docs-eslint-output-snapshots/no-base-to-string.shot b/packages/eslint-plugin/tests/docs-eslint-output-snapshots/no-base-to-string.shot
index ac8bfaecc474..ae8614ebe762 100644
--- a/packages/eslint-plugin/tests/docs-eslint-output-snapshots/no-base-to-string.shot
+++ b/packages/eslint-plugin/tests/docs-eslint-output-snapshots/no-base-to-string.shot
@@ -56,3 +56,9 @@ let value = /regex/;
 value.toString();
 let text = `${value}`;
 String(/regex/);
+
+Options: { "checkUnknown": true }
+
+declare const x: unknown;
+String(x);
+       ~ 'x' may use Object's default stringification format ('[object Object]') when stringified.
diff --git a/packages/eslint-plugin/tests/rules/no-base-to-string.test.ts b/packages/eslint-plugin/tests/rules/no-base-to-string.test.ts
index f0fe39979c4d..5fb889131b67 100644
--- a/packages/eslint-plugin/tests/rules/no-base-to-string.test.ts
+++ b/packages/eslint-plugin/tests/rules/no-base-to-string.test.ts
@@ -475,15 +475,6 @@ declare const bb: ExtendedGuildChannel;
 bb.toString();
     `,
     `
-function foo<T>(x: T) {
-  String(x);
-}
-    `,
-    `
-declare const u: unknown;
-String(u);
-    `,
-    `
 type Value = string | Value[];
 declare const v: Value;
 
@@ -511,8 +502,202 @@ String(v);
 declare const v: ('foo' | 'bar')[][];
 String(v);
     `,
+    `
+declare const x: unknown;
+\`\${x})\`;
+    `,
+    `
+declare const x: unknown;
+x.toString();
+    `,
+    `
+declare const x: unknown;
+x.toLocaleString();
+    `,
+    `
+declare const x: unknown;
+'' + x;
+    `,
+    `
+declare const x: unknown;
+String(x);
+    `,
+    `
+declare const x: unknown;
+'' += x;
+    `,
+    `
+function foo<T>(x: T) {
+  String(x);
+}
+    `,
+    `
+declare const x: any;
+\`\${x})\`;
+    `,
+    `
+declare const x: any;
+x.toString();
+    `,
+    `
+declare const x: any;
+x.toLocaleString();
+    `,
+    `
+declare const x: any;
+'' + x;
+    `,
+    `
+declare const x: any;
+String(x);
+    `,
+    `
+declare const x: any;
+'' += x;
+    `,
   ],
   invalid: [
+    {
+      code: `
+declare const x: unknown;
+\`\${x})\`;
+      `,
+      errors: [
+        {
+          data: {
+            certainty: 'may',
+            name: 'x',
+          },
+          messageId: 'baseToString',
+        },
+      ],
+      options: [
+        {
+          checkUnknown: true,
+        },
+      ],
+    },
+    {
+      code: `
+declare const x: unknown;
+x.toString();
+      `,
+      errors: [
+        {
+          data: {
+            certainty: 'may',
+            name: 'x',
+          },
+          messageId: 'baseToString',
+        },
+      ],
+      options: [
+        {
+          checkUnknown: true,
+        },
+      ],
+    },
+    {
+      code: `
+declare const x: unknown;
+x.toLocaleString();
+      `,
+      errors: [
+        {
+          data: {
+            certainty: 'may',
+            name: 'x',
+          },
+          messageId: 'baseToString',
+        },
+      ],
+      options: [
+        {
+          checkUnknown: true,
+        },
+      ],
+    },
+    {
+      code: `
+declare const x: unknown;
+'' + x;
+      `,
+      errors: [
+        {
+          data: {
+            certainty: 'may',
+            name: 'x',
+          },
+          messageId: 'baseToString',
+        },
+      ],
+      options: [
+        {
+          checkUnknown: true,
+        },
+      ],
+    },
+    {
+      code: `
+declare const x: unknown;
+String(x);
+      `,
+      errors: [
+        {
+          data: {
+            certainty: 'may',
+            name: 'x',
+          },
+          messageId: 'baseToString',
+        },
+      ],
+      options: [
+        {
+          checkUnknown: true,
+        },
+      ],
+    },
+    {
+      code: `
+declare const x: unknown;
+'' += x;
+      `,
+      errors: [
+        {
+          data: {
+            certainty: 'may',
+            name: 'x',
+          },
+          messageId: 'baseToString',
+        },
+      ],
+      options: [
+        {
+          checkUnknown: true,
+        },
+      ],
+    },
+    {
+      code: `
+function foo<T>(x: T) {
+  String(x);
+}
+      `,
+      errors: [
+        {
+          data: {
+            certainty: 'may',
+            name: 'x',
+          },
+          messageId: 'baseToString',
+        },
+      ],
+      options: [
+        {
+          checkUnknown: true,
+        },
+      ],
+    },
     {
       code: '`${{}})`;',
       errors: [
diff --git a/packages/eslint-plugin/tests/schema-snapshots/no-base-to-string.shot b/packages/eslint-plugin/tests/schema-snapshots/no-base-to-string.shot
index fe2577cd6329..207398f5c070 100644
--- a/packages/eslint-plugin/tests/schema-snapshots/no-base-to-string.shot
+++ b/packages/eslint-plugin/tests/schema-snapshots/no-base-to-string.shot
@@ -5,6 +5,10 @@
   {
     "additionalProperties": false,
     "properties": {
+      "checkUnknown": {
+        "description": "Whether to also check values of type `unknown`",
+        "type": "boolean"
+      },
       "ignoredTypeNames": {
         "description": "Stringified regular expressions of type names to ignore.",
         "items": {
@@ -22,6 +26,8 @@
 
 type Options = [
   {
+    /** Whether to also check values of type `unknown` */
+    checkUnknown?: boolean;
     /** Stringified regular expressions of type names to ignore. */
     ignoredTypeNames?: string[];
   },