diff --git a/pkg/dart2wasm/lib/translator.dart b/pkg/dart2wasm/lib/translator.dart
index 357de979bfe..4220112bd03 100644
--- a/pkg/dart2wasm/lib/translator.dart
+++ b/pkg/dart2wasm/lib/translator.dart
@@ -301,6 +301,12 @@ class Translator with KernelNodes {
     w.NumType.f64: boxedDoubleClass,
   };
 
+  late final Set<Class> boxClasses = {
+    boxedBoolClass,
+    boxedIntClass,
+    boxedDoubleClass,
+  };
+
   /// Classes whose identity hash code is their hash code rather than the
   /// identity hash code field in the struct. Each implementation class maps to
   /// the class containing the implementation of its `hashCode` getter.
@@ -689,7 +695,7 @@ class Translator with KernelNodes {
   bool isWasmType(Class cls) =>
       cls == wasmTypesBaseClass || _hasSuperclass(cls, wasmTypesBaseClass);
 
-  w.StorageType translateStorageType(DartType type) {
+  w.StorageType translateStorageType(DartType type, {bool unbox = true}) {
     bool nullable = type.isPotentiallyNullable;
     if (type is InterfaceType) {
       Class cls = type.classNode;
@@ -741,7 +747,8 @@ class Translator with KernelNodes {
       }
 
       // Other built-in type?
-      w.StorageType? builtin = builtinTypes[cls];
+      w.StorageType? builtin =
+          (unbox || !boxClasses.contains(cls)) ? builtinTypes[cls] : null;
       if (builtin != null) {
         if (!nullable) {
           return builtin;
@@ -816,8 +823,10 @@ class Translator with KernelNodes {
     while (type is TypeParameterType) {
       type = type.bound;
     }
-    return wasmArrayType(
-        translateStorageType(type), type.toText(defaultAstTextStrategy),
+    // If we write `WasmArray<BoxedInt>` we actually want an array of boxed
+    // integers and not a `WasmArray<WasmI64>`.
+    return wasmArrayType(translateStorageType(type, unbox: false),
+        type.toText(defaultAstTextStrategy),
         mutable: mutable);
   }
 
diff --git a/sdk/lib/_internal/wasm/lib/convert_patch.dart b/sdk/lib/_internal/wasm/lib/convert_patch.dart
index 21752fb1db9..f86ffcb669e 100644
--- a/sdk/lib/_internal/wasm/lib/convert_patch.dart
+++ b/sdk/lib/_internal/wasm/lib/convert_patch.dart
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import "dart:_boxed_int";
 import "dart:_compact_hash" show createMapFromStringKeyValueListUnsafe;
 import "dart:_error_utils";
 import "dart:_internal"
@@ -176,6 +177,15 @@ class _JsonListener {
     this.value = value;
   }
 
+  @pragma('wasm:prefer-inline')
+  void handleIntegerNumber(int value) {
+    if (value.toWasmI64().leU(0xff.toWasmI64())) {
+      handleNumber(_intBoxes256[value]);
+      return;
+    }
+    handleNumber(value);
+  }
+
   void handleNumber(num value) {
     this.value = value;
   }
@@ -1433,7 +1443,7 @@ mixin _ChunkedJsonParser<T> on _ChunkedJsonParserState {
 
   void finishChunkNumber(int state, int start, int end) {
     if (state == NUM_ZERO) {
-      listener.handleNumber(0);
+      listener.handleIntegerNumber(0);
       numberBuffer.clear();
       return;
     }
@@ -1578,7 +1588,7 @@ mixin _ChunkedJsonParser<T> on _ChunkedJsonParserState {
     if (!isDouble) {
       int bitFlag = -(sign + 1) >> 1; // 0 if sign == -1, -1 if sign == 1
       // Negate if bitFlag is -1 by doing ~intValue + 1
-      listener.handleNumber((intValue ^ bitFlag) - bitFlag);
+      listener.handleIntegerNumber((intValue ^ bitFlag) - bitFlag);
       return position;
     }
     // Double values at or above this value (2 ** 53) may have lost precision.
@@ -2795,3 +2805,38 @@ double _jsParseFloat(String string) => JS<double>(
   '(s) => parseFloat(s)',
   jsStringFromDartString(string).toExternRef,
 );
+
+const ImmutableWasmArray<BoxedInt> _intBoxes256 = ImmutableWasmArray.literal([
+  0, 1, 2, 3, 4, 5, 6, 7, //
+  8, 9, 10, 11, 12, 13, 14, 15, //
+  16, 17, 18, 19, 20, 21, 22, 23, //
+  24, 25, 26, 27, 28, 29, 30, 31, //
+  32, 33, 34, 35, 36, 37, 38, 39, //
+  40, 41, 42, 43, 44, 45, 46, 47, //
+  48, 49, 50, 51, 52, 53, 54, 55, //
+  56, 57, 58, 59, 60, 61, 62, 63, //
+  64, 65, 66, 67, 68, 69, 70, 71, //
+  72, 73, 74, 75, 76, 77, 78, 79, //
+  80, 81, 82, 83, 84, 85, 86, 87, //
+  88, 89, 90, 91, 92, 93, 94, 95, //
+  96, 97, 98, 99, 100, 101, 102, 103, //
+  104, 105, 106, 107, 108, 109, 110, 111, //
+  112, 113, 114, 115, 116, 117, 118, 119, //
+  120, 121, 122, 123, 124, 125, 126, 127, //
+  128, 129, 130, 131, 132, 133, 134, 135, //
+  136, 137, 138, 139, 140, 141, 142, 143, //
+  144, 145, 146, 147, 148, 149, 150, 151, //
+  152, 153, 154, 155, 156, 157, 158, 159, //
+  160, 161, 162, 163, 164, 165, 166, 167, //
+  168, 169, 170, 171, 172, 173, 174, 175, //
+  176, 177, 178, 179, 180, 181, 182, 183, //
+  184, 185, 186, 187, 188, 189, 190, 191, //
+  192, 193, 194, 195, 196, 197, 198, 199, //
+  200, 201, 202, 203, 204, 205, 206, 207, //
+  208, 209, 210, 211, 212, 213, 214, 215, //
+  216, 217, 218, 219, 220, 221, 222, 223, //
+  224, 225, 226, 227, 228, 229, 230, 231, //
+  232, 233, 234, 235, 236, 237, 238, 239, //
+  240, 241, 242, 243, 244, 245, 246, 247, //
+  248, 249, 250, 251, 252, 253, 254, 255, //
+]);