diff --git a/packages/flutter/lib/src/material/input_border.dart b/packages/flutter/lib/src/material/input_border.dart
index a0ddae07d1d..84d73aebeb9 100644
--- a/packages/flutter/lib/src/material/input_border.dart
+++ b/packages/flutter/lib/src/material/input_border.dart
@@ -254,15 +254,15 @@ class UnderlineInputBorder extends InputBorder {
         bottomRight: borderRadius.bottomRight.clamp(maximum: Radius.circular(rect.height / 2)),
       );
 
-      // We set the strokeAlign to center, so the behavior is consistent with
-      // drawLine and with the historical behavior of this border.
       BoxBorder.paintNonUniformBorder(canvas, rect,
-          textDirection: textDirection,
-          borderRadius: updatedBorderRadius,
-          bottom: borderSide.copyWith(strokeAlign: BorderSide.strokeAlignCenter),
-          color: borderSide.color);
+        textDirection: textDirection,
+        borderRadius: updatedBorderRadius,
+        bottom: borderSide.copyWith(strokeAlign: BorderSide.strokeAlignInside),
+        color: borderSide.color,
+      );
     } else {
-      canvas.drawLine(rect.bottomLeft, rect.bottomRight, borderSide.toPaint());
+      final Offset alignInsideOffset = Offset(0, borderSide.width / 2);
+      canvas.drawLine(rect.bottomLeft - alignInsideOffset, rect.bottomRight - alignInsideOffset, borderSide.toPaint());
     }
   }
 
diff --git a/packages/flutter/test/material/input_decorator_test.dart b/packages/flutter/test/material/input_decorator_test.dart
index 7061dbf4ce5..7a68461f511 100644
--- a/packages/flutter/test/material/input_decorator_test.dart
+++ b/packages/flutter/test/material/input_decorator_test.dart
@@ -1537,17 +1537,70 @@ void main() {
 
       // Fill is the border's outer path, a rounded rectangle.
       expect(box, paints
-      ..drrect(
-        style: PaintingStyle.fill,
-        inner: RRect.fromLTRBAndCorners(0.0, 0.0, 800.0, 47.5,
-            bottomRight: const Radius.elliptical(12.0, 11.5),
-            bottomLeft: const Radius.elliptical(12.0, 11.5)),
-        outer: RRect.fromLTRBAndCorners(0.0, 0.0, 800.0, 48.5,
-            bottomRight: const Radius.elliptical(12.0, 12.5),
-            bottomLeft: const Radius.elliptical(12.0, 12.5)),
+        ..drrect(
+          style: PaintingStyle.fill,
+          inner: RRect.fromLTRBAndCorners(0.0, 0.0, 800.0, 47.0,
+              bottomRight: const Radius.elliptical(12.0, 11.0),
+              bottomLeft: const Radius.elliptical(12.0, 11.0)),
+          outer: RRect.fromLTRBAndCorners(0.0, 0.0, 800.0, 48.0,
+              bottomRight: const Radius.elliptical(12.0, 12.0),
+              bottomLeft: const Radius.elliptical(12.0, 12.0)),
       ));
     });
 
+    testWidgets('UnderlineInputBorder clips top border to prevent anti-aliasing glitches', (WidgetTester tester) async {
+      const Rect canvasRect = Rect.fromLTWH(0, 0, 100, 100);
+      const UnderlineInputBorder border = UnderlineInputBorder(
+        borderRadius: BorderRadius.all(Radius.circular(12.0)),
+      );
+      expect(
+        (Canvas canvas) => border.paint(canvas, canvasRect),
+        paints
+          ..drrect(
+            outer: RRect.fromLTRBAndCorners(0.0, 0.0, 100.0, 100.0,
+                bottomRight: const Radius.elliptical(12.0, 12.0),
+                bottomLeft: const Radius.elliptical(12.0, 12.0)),
+            inner: RRect.fromLTRBAndCorners(0.0, 0.0, 100.0, 99.0,
+                bottomRight: const Radius.elliptical(12.0, 11.0),
+                bottomLeft: const Radius.elliptical(12.0, 11.0)),
+          ),
+      );
+
+      const UnderlineInputBorder border2 = UnderlineInputBorder(
+        borderRadius: BorderRadius.all(Radius.circular(60.0)),
+      );
+      expect(
+        (Canvas canvas) => border2.paint(canvas, canvasRect),
+        paints
+          ..drrect(
+            outer: RRect.fromLTRBAndCorners(0.0, 0.0, 100.0, 100.0,
+                bottomRight: const Radius.elliptical(50.0, 50.0),
+                bottomLeft: const Radius.elliptical(50.0, 50.0)),
+            inner: RRect.fromLTRBAndCorners(0.0, 0.0, 100.0, 99.0,
+                bottomRight: const Radius.elliptical(50.0, 49.0),
+                bottomLeft: const Radius.elliptical(50.0, 49.0)),
+          ),
+        reason: 'clamp is expected',
+      );
+    });
+
+    testWidgets('UnderlineInputBorder draws bottom border inside container bounds', (WidgetTester tester) async {
+      const Rect canvasRect = Rect.fromLTWH(0, 0, 100, 100);
+      const double borderWidth = 2.0;
+      const UnderlineInputBorder border = UnderlineInputBorder(
+        borderSide: BorderSide(width: borderWidth),
+      );
+      expect(
+        (Canvas canvas) => border.paint(canvas, canvasRect),
+        paints
+          ..line(
+            p1: Offset(0, canvasRect.height - borderWidth / 2),
+            p2: Offset(100, canvasRect.height - borderWidth / 2),
+            strokeWidth: borderWidth,
+          ),
+      );
+    });
+
     testWidgets('InputDecorator OutlineBorder focused label with icon', (WidgetTester tester) async {
       // This is a regression test for https://github.com/flutter/flutter/issues/82321
       Widget buildFrame(TextDirection textDirection) {
@@ -5174,42 +5227,6 @@ void main() {
     });
   });
 
-  testWidgets('UnderlineInputBorder clips top border to prevent anti-aliasing glitches', (WidgetTester tester) async {
-    const Rect canvasRect = Rect.fromLTWH(0, 0, 100, 100);
-    const UnderlineInputBorder border = UnderlineInputBorder(
-      borderRadius: BorderRadius.all(Radius.circular(12.0)),
-    );
-    expect(
-      (Canvas canvas) => border.paint(canvas, canvasRect),
-      paints
-        ..drrect(
-          outer: RRect.fromLTRBAndCorners(0.0, 0.0, 100.0, 100.5,
-                bottomRight: const Radius.elliptical(12.0, 12.5),
-                bottomLeft: const Radius.elliptical(12.0, 12.5)),
-          inner: RRect.fromLTRBAndCorners(0.0, 0.0, 100.0, 99.5,
-                bottomRight: const Radius.elliptical(12.0, 11.5),
-                bottomLeft: const Radius.elliptical(12.0, 11.5)),
-        ),
-    );
-
-    const UnderlineInputBorder border2 = UnderlineInputBorder(
-      borderRadius: BorderRadius.all(Radius.circular(60.0)),
-    );
-    expect(
-      (Canvas canvas) => border2.paint(canvas, canvasRect),
-      paints
-        ..drrect(
-          outer: RRect.fromLTRBAndCorners(0.0, 0.0, 100.0, 100.5,
-                bottomRight: const Radius.elliptical(50.0, 50.5),
-                bottomLeft: const Radius.elliptical(50.0, 50.5)),
-          inner: RRect.fromLTRBAndCorners(0.0, 0.0, 100.0, 99.5,
-                bottomRight: const Radius.elliptical(50.0, 49.5),
-                bottomLeft: const Radius.elliptical(50.0, 49.5)),
-        ),
-      reason: 'clamp is expected',
-    );
-  });
-
   testWidgets('Ensure the height of labelStyle remains unchanged when TextField is focused', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/141448.
     final FocusNode focusNode = FocusNode();
@@ -9754,12 +9771,12 @@ void main() {
       expect(box, paints
       ..drrect(
         style: PaintingStyle.fill,
-        inner: RRect.fromLTRBAndCorners(0.0, 0.0, 800.0, 47.5,
-            bottomRight: const Radius.elliptical(12.0, 11.5),
-            bottomLeft: const Radius.elliptical(12.0, 11.5)),
-        outer: RRect.fromLTRBAndCorners(0.0, 0.0, 800.0, 48.5,
-            bottomRight: const Radius.elliptical(12.0, 12.5),
-            bottomLeft: const Radius.elliptical(12.0, 12.5)),
+        inner: RRect.fromLTRBAndCorners(0.0, 0.0, 800.0, 47.0,
+            bottomRight: const Radius.elliptical(12.0, 11.0),
+            bottomLeft: const Radius.elliptical(12.0, 11.0)),
+        outer: RRect.fromLTRBAndCorners(0.0, 0.0, 800.0, 48.0,
+            bottomRight: const Radius.elliptical(12.0, 12.0),
+            bottomLeft: const Radius.elliptical(12.0, 12.0)),
       ));
     });