diff --git a/CHANGELOG.md b/CHANGELOG.md
index 88efba3d31..4a887a8bcc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+### Fixes
+
+- Memory leak when finishing an unsampled Transaction that has started unsampled Spans ([#4717](https://github.com/getsentry/sentry-dotnet/pull/4717))
+  - backported via ([#4853](https://github.com/getsentry/sentry-dotnet/pull/4853))
+
 ### Dependencies
 
 - Bump Java SDK from v8.24.0 to v8.25.0 ([#4679](https://github.com/getsentry/sentry-dotnet/pull/4679))
diff --git a/src/Sentry/Internal/UnsampledTransaction.cs b/src/Sentry/Internal/UnsampledTransaction.cs
index 8f55b7d808..8277262458 100644
--- a/src/Sentry/Internal/UnsampledTransaction.cs
+++ b/src/Sentry/Internal/UnsampledTransaction.cs
@@ -4,7 +4,7 @@ namespace Sentry.Internal;
 
 /// <summary>
 /// We know already, when starting a transaction, whether it's going to be sampled or not. When it's not sampled, we can
-/// avoid lots of unecessary processing. The only thing we need to track is the number of spans that would have been
+/// avoid lots of unnecessary processing. The only thing we need to track is the number of spans that would have been
 /// created (the client reports detailing discarded events includes this detail).
 /// </summary>
 internal sealed class UnsampledTransaction : NoOpTransaction
@@ -12,7 +12,12 @@ internal sealed class UnsampledTransaction : NoOpTransaction
     // Although it's a little bit wasteful to create separate individual class instances here when all we're going to
     // report to sentry is the span count (in the client report), SDK users may refer to things like
     // `ITransaction.Spans.Count`, so we create an actual collection
+#if NETCOREAPP2_0_OR_GREATER || NETSTANDARD2_1_OR_GREATER
     private readonly ConcurrentBag<ISpan> _spans = [];
+#else
+    private ConcurrentBag<ISpan> _spans = [];
+#endif
+
     private readonly IHub _hub;
     private readonly ITransactionContext _context;
     private readonly SentryOptions? _options;
@@ -79,6 +84,9 @@ public override void Finish()
         _options?.ClientReportRecorder.RecordDiscardedEvent(discardReason, DataCategory.Span, spanCount);
 
         _options?.LogDebug("Finished unsampled transaction");
+
+        // Release tracked spans
+        ReleaseSpans();
     }
 
     public override void Finish(SpanStatus status) => Finish();
@@ -103,4 +111,13 @@ public ISpan StartChild(string operation, SpanId spanId)
         _spans.Add(span);
         return span;
     }
+
+    private void ReleaseSpans()
+    {
+#if NETCOREAPP2_0_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        _spans.Clear();
+#else
+        _spans = [];
+#endif
+    }
 }
diff --git a/src/Sentry/TransactionTracer.cs b/src/Sentry/TransactionTracer.cs
index 1f965deef6..2c9e322baf 100644
--- a/src/Sentry/TransactionTracer.cs
+++ b/src/Sentry/TransactionTracer.cs
@@ -167,7 +167,7 @@ public IReadOnlyList<string> Fingerprint
     /// <inheritdoc />
     public IReadOnlyDictionary<string, string> Tags => _tags;
 
-#if NETSTANDARD2_1_OR_GREATER
+#if NETCOREAPP2_0_OR_GREATER || NETSTANDARD2_1_OR_GREATER
     private readonly ConcurrentBag<ISpan> _spans = new();
 #else
     private ConcurrentBag<ISpan> _spans = new();
@@ -429,7 +429,7 @@ public string? Origin
 
     private void ReleaseSpans()
     {
-#if NETSTANDARD2_1_OR_GREATER
+#if NETCOREAPP2_0_OR_GREATER || NETSTANDARD2_1_OR_GREATER
         _spans.Clear();
 #else
         _spans = new ConcurrentBag<ISpan>();
diff --git a/test/Sentry.Tests/Internals/UnsampledSpanTests.cs b/test/Sentry.Tests/Internals/UnsampledSpanTests.cs
index a64edc9eed..338eb4e639 100644
--- a/test/Sentry.Tests/Internals/UnsampledSpanTests.cs
+++ b/test/Sentry.Tests/Internals/UnsampledSpanTests.cs
@@ -2,6 +2,24 @@ namespace Sentry.Tests.Internals;
 
 public class UnsampledSpanTests
 {
+    [Fact]
+    public void StartChild_IsUnsampledSpan_HasReferenceToUnsampledTransaction()
+    {
+        // Arrange
+        var hub = Substitute.For<IHub>();
+        ITransactionContext context = new TransactionContext("TestTransaction", "TestOperation",
+            new SentryTraceHeader(SentryId.Create(), SpanId.Create(), false)
+        );
+        var transaction = new UnsampledTransaction(hub, context);
+
+        // Act
+        var unsampledSpan = transaction.StartChild("Foo");
+
+        // Assert
+        Assert.IsType<UnsampledSpan>(unsampledSpan);
+        Assert.Same(transaction, unsampledSpan.GetTransaction());
+    }
+
     [Fact]
     public void GetTraceHeader_CreatesHeaderFromUnsampledTransaction()
     {
diff --git a/test/Sentry.Tests/Internals/UnsampledTransactionTests.cs b/test/Sentry.Tests/Internals/UnsampledTransactionTests.cs
new file mode 100644
index 0000000000..679e907826
--- /dev/null
+++ b/test/Sentry.Tests/Internals/UnsampledTransactionTests.cs
@@ -0,0 +1,40 @@
+namespace Sentry.Tests.Internals;
+
+public class UnsampledTransactionTests
+{
+    [Fact]
+    public void StartChild_CreatesSpan_IsTrackedByParent()
+    {
+        // Arrange
+        var hub = Substitute.For<IHub>();
+        ITransactionContext context = new TransactionContext("TestTransaction", "TestOperation",
+            new SentryTraceHeader(SentryId.Create(), SpanId.Create(), false)
+        );
+        var transaction = new UnsampledTransaction(hub, context);
+
+        // Act
+        var unsampledSpan = transaction.StartChild("Foo");
+
+        // Assert
+        var span = Assert.Single(transaction.Spans);
+        Assert.Same(unsampledSpan, span);
+    }
+
+    [Fact]
+    public void Finish_WithTrackedSpans_ClearsTrackedSpans()
+    {
+        // Arrange
+        var hub = Substitute.For<IHub>();
+        ITransactionContext context = new TransactionContext("TestTransaction", "TestOperation",
+            new SentryTraceHeader(SentryId.Create(), SpanId.Create(), false)
+        );
+        var transaction = new UnsampledTransaction(hub, context);
+        _ = transaction.StartChild("Foo");
+
+        // Act
+        transaction.Finish();
+
+        // Assert
+        Assert.Empty(transaction.Spans);
+    }
+}
diff --git a/test/Sentry.Tests/SpanTracerTests.cs b/test/Sentry.Tests/SpanTracerTests.cs
index 59becf2740..ee51246f70 100644
--- a/test/Sentry.Tests/SpanTracerTests.cs
+++ b/test/Sentry.Tests/SpanTracerTests.cs
@@ -10,7 +10,7 @@ public async Task SetExtra_DataInserted_NoDataLoss()
         {
             // Arrange
             var hub = Substitute.For<IHub>();
-            var transaction = new SpanTracer(hub, null, null, SentryId.Empty, "");
+            var spanTracer = new SpanTracer(hub, null, null, SentryId.Empty, "");
             var evt = new ManualResetEvent(false);
             var ready = new ManualResetEvent(false);
             var counter = 0;
@@ -27,7 +27,7 @@ public async Task SetExtra_DataInserted_NoDataLoss()
 
                 for (var i = 0; i < amount; i++)
                 {
-                    transaction.SetExtra(Guid.NewGuid().ToString(), Guid.NewGuid());
+                    spanTracer.SetExtra(Guid.NewGuid().ToString(), Guid.NewGuid());
                 }
             })).ToList();
             ready.WaitOne();
@@ -36,7 +36,7 @@ public async Task SetExtra_DataInserted_NoDataLoss()
 
             // Arrange
             // 4 tasks testing X amount should be the same amount as Extras.
-            Assert.Equal(4 * amount, transaction.Extra.Count);
+            Assert.Equal(4 * amount, spanTracer.Extra.Count);
         }
     }
 }
diff --git a/test/Sentry.Tests/TransactionTracerTests.cs b/test/Sentry.Tests/TransactionTracerTests.cs
new file mode 100644
index 0000000000..2c4e282a23
--- /dev/null
+++ b/test/Sentry.Tests/TransactionTracerTests.cs
@@ -0,0 +1,35 @@
+namespace Sentry.Tests;
+
+public class TransactionTracerTests
+{
+    [Fact]
+    public void StartChild_CreatesSpanTracer_TracksSpans()
+    {
+        // Arrange
+        var hub = Substitute.For<IHub>();
+        var transaction = new TransactionTracer(hub, "op", "name");
+
+        // Act
+        var span = transaction.StartChild("operation");
+
+        // Assert
+        Assert.IsType<SpanTracer>(span);
+        Assert.Collection(transaction.Spans,
+            element => Assert.Same(span, element));
+    }
+
+    [Fact]
+    public void Finish_WithTrackedSpans_ClearsTrackedSpans()
+    {
+        // Arrange
+        var hub = Substitute.For<IHub>();
+        var transaction = new TransactionTracer(hub, "op", "name");
+        _ = transaction.StartChild("operation");
+
+        // Act
+        transaction.Finish();
+
+        // Assert
+        Assert.Empty(transaction.Spans);
+    }
+}