diff --git a/packages/router-core/src/qss.ts b/packages/router-core/src/qss.ts
index 5b1b733324..f6ba5f990b 100644
--- a/packages/router-core/src/qss.ts
+++ b/packages/router-core/src/qss.ts
@@ -39,23 +39,6 @@ export function encode(
   return result.toString()
 }
 
-/**
- * Converts a string value to its appropriate type (string, number, boolean).
- * @param mix - The string value to convert.
- * @returns The converted value.
- * @example
- * // Example input: toValue("123")
- * // Expected output: 123
- */
-/** Convert a string into a primitive boolean/number when possible. */
-function toValue(str: unknown) {
-  if (!str) return ''
-
-  if (str === 'false') return false
-  if (str === 'true') return true
-  return +str * 0 === 0 && +str + '' === str ? +str : str
-}
-
 /**
  * Decodes a query string into an object.
  * @param str - The query string to decode.
@@ -73,11 +56,11 @@ export function decode(str: any): any {
   for (const [key, value] of searchParams.entries()) {
     const previousValue = result[key]
     if (previousValue == null) {
-      result[key] = toValue(value)
+      result[key] = value
     } else if (Array.isArray(previousValue)) {
-      previousValue.push(toValue(value))
+      previousValue.push(value)
     } else {
-      result[key] = [previousValue, toValue(value)]
+      result[key] = [previousValue, value]
     }
   }
 
diff --git a/packages/router-core/src/searchParams.ts b/packages/router-core/src/searchParams.ts
index ad9957aed9..ee5c29e886 100644
--- a/packages/router-core/src/searchParams.ts
+++ b/packages/router-core/src/searchParams.ts
@@ -35,7 +35,10 @@ export function parseSearchWith(parser: (str: string) => any) {
       const value = query[key]
       if (typeof value === 'string') {
         try {
-          query[key] = parser(value)
+          const parsed = parser(value)
+          if (parsed && typeof parsed === 'object') {
+            query[key] = parsed
+          }
         } catch (_err) {
           // silent
         }
@@ -75,8 +78,10 @@ export function stringifySearchWith(
       try {
         // Check if it's a valid parseable string.
         // If it is, then stringify it again.
-        parser(val)
-        return stringify(val)
+        const parsed = parser(val)
+        if (parsed && typeof parsed === 'object') {
+          return stringify(val)
+        }
       } catch (_err) {
         // silent
       }
diff --git a/packages/router-core/tests/qss.test.ts b/packages/router-core/tests/qss.test.ts
index ce92857ab5..fc228c779a 100644
--- a/packages/router-core/tests/qss.test.ts
+++ b/packages/router-core/tests/qss.test.ts
@@ -61,7 +61,7 @@ describe('decode function', () => {
   it('should handle decoding a top-level key with a special character', () => {
     const queryString = 'foo%3Dbar=1'
     const decodedObj = decode(queryString)
-    expect(decodedObj).toEqual({ 'foo=bar': 1 })
+    expect(decodedObj).toEqual({ 'foo=bar': '1' })
   })
 
   it('should handle decoding a top-level key with a special character and without a value', () => {
diff --git a/packages/router-core/tests/searchParams.test.ts b/packages/router-core/tests/searchParams.test.ts
index 006e119be5..c8dc204a6e 100644
--- a/packages/router-core/tests/searchParams.test.ts
+++ b/packages/router-core/tests/searchParams.test.ts
@@ -2,43 +2,43 @@ import { describe, expect, test } from 'vitest'
 import { defaultParseSearch, defaultStringifySearch } from '../src'
 
 describe('Search Params serialization and deserialization', () => {
-  /*
-   * JSON-compatible objects can be serialized into a string,
-   * and then deserialized back into the original object.
-   */
   test.each([
-    [{}, ''],
-    [{ foo: '' }, '?foo='],
-    [{ foo: 'bar' }, '?foo=bar'],
-    [{ foo: 'bar baz' }, '?foo=bar+baz'],
-    [{ foo: 123 }, '?foo=123'],
-    [{ foo: '123' }, '?foo=%22123%22'],
-    [{ foo: true }, '?foo=true'],
-    [{ foo: 'true' }, '?foo=%22true%22'],
-    [{ foo: null }, '?foo=null'],
-    [{ foo: 'null' }, '?foo=%22null%22'],
-    [{ foo: 'undefined' }, '?foo=undefined'],
-    [{ foo: {} }, '?foo=%7B%7D'],
-    [{ foo: '{}' }, '?foo=%22%7B%7D%22'],
-    [{ foo: [] }, '?foo=%5B%5D'],
-    [{ foo: '[]' }, '?foo=%22%5B%5D%22'],
-    [{ foo: [1, 2, 3] }, '?foo=%5B1%2C2%2C3%5D'],
-    [{ foo: '1,2,3' }, '?foo=1%2C2%2C3'],
-    [{ foo: { bar: 'baz' } }, '?foo=%7B%22bar%22%3A%22baz%22%7D'],
-    [{ 0: 1 }, '?0=1'],
-    [{ 'foo=bar': 1 }, '?foo%3Dbar=1'],
-    [{ '{}': 1 }, '?%7B%7D=1'],
-    [{ '': 1 }, '?=1'],
-    [{ '=': '=' }, '?%3D=%3D'],
-    [{ '=': '', '': '=' }, '?%3D=&=%3D'],
-    [{ 'foo=2&bar': 3 }, '?foo%3D2%26bar=3'],
-    [{ 'foo?': 1 }, '?foo%3F=1'],
-    [{ foo: 'bar=' }, '?foo=bar%3D'],
-    [{ foo: '2&bar=3' }, '?foo=2%26bar%3D3'],
-  ])('isomorphism %j', (input, expected) => {
-    const str = defaultStringifySearch(input)
-    expect(str).toEqual(expected)
-    expect(defaultParseSearch(str)).toEqual(input)
+    ['', {}],
+    ['?foo=', { foo: '' }],
+    ['?foo=bar', { foo: 'bar' }],
+    ['?foo=%22bar%22', { foo: '"bar"' }],
+    ['?foo=bar+baz', { foo: 'bar baz' }],
+    ['?foo=%22bar+baz%22', { foo: '"bar baz"' }],
+    ['?foo=123', { foo: '123' }],
+    ['?foo=%22123%22', { foo: '"123"' }],
+    ['?foo=true', { foo: 'true' }],
+    ['?foo=%22true%22', { foo: '"true"' }],
+    ['?foo=null', { foo: 'null' }],
+    ['?foo=%22null%22', { foo: '"null"' }],
+    ['?foo=undefined', { foo: 'undefined' }],
+    ['?foo=%22undefined%22', { foo: '"undefined"' }],
+    ['?foo=%7B%7D', { foo: {} }],
+    ['?foo=%22%7B%7D%22', { foo: '"{}"' }],
+    ['?foo=%5B%5D', { foo: [] }],
+    ['?foo=%22%5B%5D%22', { foo: '"[]"' }],
+    ['?foo=%5B1%2C2%2C3%5D', { foo: [1, 2, 3] }],
+    ['?foo=1%2C2%2C3', { foo: '1,2,3' }],
+    ['?foo=%7B%22bar%22%3A%22baz%22%7D', { foo: { bar: 'baz' } }],
+    ['?0=1', { 0: '1' }],
+    ['?foo%3Dbar=1', { 'foo=bar': '1' }],
+    ['?%7B%7D=1', { '{}': '1' }],
+    ['?=1', { '': '1' }],
+    ['?%3D=%3D', { '=': '=' }],
+    ['?%3D=&=%3D', { '=': '', '': '=' }],
+    ['?foo%3D2%26bar=3', { 'foo=2&bar': '3' }],
+    ['?foo%3F=1', { 'foo?': '1' }],
+    ['?foo=bar%3D', { foo: 'bar=' }],
+    ['?foo=2%26bar%3D3', { foo: '2&bar=3' }],
+  ])('isomorphism %j', (input, expectedObj) => {
+    const parsed = defaultParseSearch(input)
+    expect(parsed).toEqual(expectedObj)
+    const str = defaultStringifySearch(parsed)
+    expect(str).toEqual(input)
   })
 
   test('undefined values are removed during stringification', () => {
@@ -67,8 +67,8 @@ describe('Search Params serialization and deserialization', () => {
     ['?foo=[]', { foo: [] }],
     ['?foo=1,2,3', { foo: '1,2,3' }],
     ['?foo={"bar":"baz"}', { foo: { bar: 'baz' } }],
-    ['?foo=1&foo=2', { foo: [1, 2] }],
-    ['?foo=""', { foo: '' }],
+    ['?foo=1&foo=2', { foo: ['1', '2'] }],
+    ['?foo=""', { foo: '""' }],
     ['?foo=""""', { foo: '""""' }],
     ['?foo=()', { foo: '()' }],
     ['?foo=[{}]', { foo: [{}] }],