diff --git a/src/Avalonia.Controls/VirtualizingStackPanel.cs b/src/Avalonia.Controls/VirtualizingStackPanel.cs
index a8cc7b669d..62010aecc4 100644
--- a/src/Avalonia.Controls/VirtualizingStackPanel.cs
+++ b/src/Avalonia.Controls/VirtualizingStackPanel.cs
@@ -293,10 +293,28 @@ namespace Avalonia.Controls
                 // Ensure that the focused element is in the correct position.
                 if (_focusedElement is not null && _focusedIndex >= 0)
                 {
+                    var realizedEndU = u;
+                    var sizeU = orientation == Orientation.Horizontal ?
+                        _focusedElement.DesiredSize.Width :
+                        _focusedElement.DesiredSize.Height;
+
                     u = GetOrEstimateElementU(_focusedIndex);
+
+                    // The focused element's position is estimated as it's outside the realized
+                    // range. A bad estimate must not place it over the realized elements in the
+                    // viewport: an element before the realized range always ends at or before its
+                    // start, and one after it always starts at or after its end.
+                    if (_realizedElements.Count > 0 && !double.IsNaN(_realizedElements.StartU))
+                    {
+                        if (_focusedIndex < _realizedElements.FirstIndex)
+                            u = Math.Min(u, _realizedElements.StartU - sizeU);
+                        else if (_focusedIndex > _realizedElements.LastIndex)
+                            u = Math.Max(u, realizedEndU);
+                    }
+
                     var rect = orientation == Orientation.Horizontal ?
-                        new Rect(u, 0, _focusedElement.DesiredSize.Width, finalSize.Height) :
-                        new Rect(0, u, finalSize.Width, _focusedElement.DesiredSize.Height);
+                        new Rect(u, 0, sizeU, finalSize.Height) :
+                        new Rect(0, u, finalSize.Width, sizeU);
 
                     _focusedElement.Arrange(rect);
                 }
diff --git a/tests/Avalonia.Controls.UnitTests/VirtualizingStackPanelTests.cs b/tests/Avalonia.Controls.UnitTests/VirtualizingStackPanelTests.cs
index 873da11c67..f9d079835d 100644
--- a/tests/Avalonia.Controls.UnitTests/VirtualizingStackPanelTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/VirtualizingStackPanelTests.cs
@@ -492,6 +492,40 @@ namespace Avalonia.Controls.UnitTests
             Assert.Same(focused, target.GetRealizedElements().First());
         }
 
+        [Theory]
+        [InlineData(0d)]
+        [InlineData(0.5d)]
+        public void Focused_Element_Outside_Realized_Range_Is_Not_Arranged_In_Viewport(double bufferFactor)
+        {
+            using var app = App();
+
+            // Item 0 is much taller than the others, so the average-based position estimated for
+            // it once it has left the realized range lands inside the viewport (#17935).
+            var items = Enumerable.Range(0, 100).Select(x => new ItemWithHeight(x, x == 0 ? 100 : 10));
+            var (target, scroll, itemsControl) = CreateTarget(
+                items: items,
+                itemTemplate: CanvasWithHeightTemplate,
+                bufferFactor: bufferFactor);
+
+            var focused = target.GetRealizedElements().First()!;
+            focused.Focusable = true;
+            focused.Focus();
+            Assert.True(focused.IsKeyboardFocusWithin);
+
+            scroll.Offset = new Vector(0, 160);
+            Layout(target);
+
+            var viewport = new Rect(scroll.Offset.X, scroll.Offset.Y, scroll.Viewport.Width, scroll.Viewport.Height);
+            Assert.True(focused.IsKeyboardFocusWithin);
+            Assert.False(focused.Bounds.Intersects(viewport));
+
+            scroll.Offset = new Vector(0, 0);
+            Layout(target);
+
+            Assert.Same(focused, target.GetRealizedElements().First());
+            Assert.Equal(new Rect(0, 0, 100, 100), focused.Bounds);
+        }
+
         [Theory]
         [InlineData(0d)]
         [InlineData(0.5d)]