diff --git a/packages/zod/src/v4/classic/tests/to-json-schema.test.ts b/packages/zod/src/v4/classic/tests/to-json-schema.test.ts
index c50df9d7b..a2e7573d4 100644
--- a/packages/zod/src/v4/classic/tests/to-json-schema.test.ts
+++ b/packages/zod/src/v4/classic/tests/to-json-schema.test.ts
@@ -657,6 +657,54 @@ describe("toJSONSchema", () => {
     `);
   });
 
+  test("discriminated unions", () => {
+    const schema = z.discriminatedUnion("type", [
+      z.object({ type: z.literal("success"), data: z.string() }),
+      z.object({ type: z.literal("error"), message: z.string() }),
+    ]);
+    expect(z.toJSONSchema(schema)).toMatchInlineSnapshot(`
+      {
+        "$schema": "https://json-schema.org/draft/2020-12/schema",
+        "oneOf": [
+          {
+            "additionalProperties": false,
+            "properties": {
+              "data": {
+                "type": "string",
+              },
+              "type": {
+                "const": "success",
+                "type": "string",
+              },
+            },
+            "required": [
+              "type",
+              "data",
+            ],
+            "type": "object",
+          },
+          {
+            "additionalProperties": false,
+            "properties": {
+              "message": {
+                "type": "string",
+              },
+              "type": {
+                "const": "error",
+                "type": "string",
+              },
+            },
+            "required": [
+              "type",
+              "message",
+            ],
+            "type": "object",
+          },
+        ],
+      }
+    `);
+  });
+
   test("intersections", () => {
     const schema = z.intersection(z.object({ name: z.string() }), z.object({ age: z.number() }));
 
diff --git a/packages/zod/src/v4/core/to-json-schema.ts b/packages/zod/src/v4/core/to-json-schema.ts
index 429fd7614..d295ef258 100644
--- a/packages/zod/src/v4/core/to-json-schema.ts
+++ b/packages/zod/src/v4/core/to-json-schema.ts
@@ -330,13 +330,20 @@ export class JSONSchemaGenerator {
           }
           case "union": {
             const json: JSONSchema.BaseSchema = _json as any;
+            // Discriminated unions use oneOf (exactly one match) instead of anyOf (one or more matches)
+            // because the discriminator field ensures mutual exclusivity between options in JSON Schema
+            const isDiscriminated = (def as any).discriminator !== undefined;
             const options = def.options.map((x, i) =>
               this.process(x, {
                 ...params,
-                path: [...params.path, "anyOf", i],
+                path: [...params.path, isDiscriminated ? "oneOf" : "anyOf", i],
               })
             );
-            json.anyOf = options;
+            if (isDiscriminated) {
+              json.oneOf = options;
+            } else {
+              json.anyOf = options;
+            }
             break;
           }
           case "intersection": {