diff --git a/lib/sentry/opentelemetry/span_processor.ex b/lib/sentry/opentelemetry/span_processor.ex
index af16ac02..ea42d86c 100644
--- a/lib/sentry/opentelemetry/span_processor.ex
+++ b/lib/sentry/opentelemetry/span_processor.ex
@@ -27,7 +27,11 @@ if Code.ensure_loaded?(OpenTelemetry) do
 
       SpanStorage.store_span(span_record)
 
-      if span_record.parent_span_id == nil do
+      # Check if this is a root span (no parent) or a transaction root (HTTP request span)
+      is_transaction_root =
+        span_record.parent_span_id == nil or is_http_request_span?(span_record)
+
+      if is_transaction_root do
         child_span_records = SpanStorage.get_child_spans(span_record.span_id)
         transaction = build_transaction(span_record, child_span_records)
 
@@ -60,6 +64,20 @@ if Code.ensure_loaded?(OpenTelemetry) do
       :ok
     end
 
+    # Helper function to detect if a span represents an HTTP request that should be treated as a transaction root
+    defp is_http_request_span?(%{attributes: attributes, name: name}) do
+      # Check if this is an HTTP request span (has HTTP method and is likely a server span)
+      has_http_method = Map.has_key?(attributes, to_string(HTTPAttributes.http_request_method()))
+      has_http_route = Map.has_key?(attributes, "http.route")
+      has_url_path = Map.has_key?(attributes, to_string(URLAttributes.url_path()))
+
+      # Check if the name looks like an HTTP endpoint
+      name_looks_like_http =
+        String.contains?(name, ["/", "POST", "GET", "PUT", "DELETE", "PATCH"])
+
+      (has_http_method and (has_http_route or has_url_path)) or name_looks_like_http
+    end
+
     defp build_transaction(root_span_record, child_span_records) do
       root_span = build_span(root_span_record)
       child_spans = Enum.map(child_span_records, &build_span(&1))
diff --git a/test/sentry/opentelemetry/span_processor_test.exs b/test/sentry/opentelemetry/span_processor_test.exs
index 331acd08..ef8c3250 100644
--- a/test/sentry/opentelemetry/span_processor_test.exs
+++ b/test/sentry/opentelemetry/span_processor_test.exs
@@ -235,6 +235,74 @@ defmodule Sentry.Opentelemetry.SpanProcessorTest do
       assert transaction.transaction == "child_instrumented_function_standalone"
     end
 
+    @tag span_storage: true
+    test "treats HTTP request spans as transaction roots even with external parents" do
+      put_test_config(environment_name: "test", traces_sample_rate: 1.0)
+
+      Sentry.Test.start_collecting_sentry_reports()
+
+      # Simulate an HTTP request span with external parent (like from browser tracing)
+      require OpenTelemetry.Tracer, as: Tracer
+      require OpenTelemetry.SemConv.Incubating.HTTPAttributes, as: HTTPAttributes
+      require OpenTelemetry.SemConv.Incubating.URLAttributes, as: URLAttributes
+
+      # Create a span with HTTP attributes and an external parent span ID
+      external_parent_span_id = "b943d7459127970c"
+
+      # Start a span that simulates an HTTP request from an external trace
+      Tracer.with_span "POST /api/v1alpha", %{
+        attributes: %{
+          HTTPAttributes.http_request_method() => :POST,
+          URLAttributes.url_path() => "/api/v1alpha",
+          "http.route" => "/api/v1alpha",
+          "server.address" => "localhost",
+          "server.port" => 4000
+        },
+        parent:
+          {:span_context, :undefined, external_parent_span_id, :undefined, :undefined, :undefined,
+           :undefined, :undefined, :undefined, :undefined}
+      } do
+        # Simulate child spans (database queries, etc.) with proper DB attributes
+        Tracer.with_span "matrix_data.repo.query", %{
+          attributes: %{
+            "db.system" => :postgresql,
+            "db.statement" => "SELECT * FROM users"
+          }
+        } do
+          Process.sleep(10)
+        end
+
+        Tracer.with_span "matrix_data.repo.query:agents", %{
+          attributes: %{
+            "db.system" => :postgresql,
+            "db.statement" => "INSERT INTO agents (...) VALUES (...)"
+          }
+        } do
+          Process.sleep(10)
+        end
+      end
+
+      # Should capture the HTTP request span as a transaction root despite having an external parent
+      assert [%Sentry.Transaction{} = transaction] = Sentry.Test.pop_sentry_transactions()
+
+      # Verify transaction properties
+      assert transaction.transaction == "POST /api/v1alpha"
+      assert transaction.transaction_info == %{source: :custom}
+      assert length(transaction.spans) == 2
+
+      # Verify child spans are properly included - they should have "db" operation
+      span_names = Enum.map(transaction.spans, & &1.op) |> Enum.sort()
+      expected_names = ["db", "db"]
+      assert span_names == expected_names
+
+      # Verify all spans share the same trace ID
+      trace_id = transaction.contexts.trace.trace_id
+
+      Enum.each(transaction.spans, fn span ->
+        assert span.trace_id == trace_id
+      end)
+    end
+
     @tag span_storage: true
     test "concurrent traces maintain independent sampling decisions" do
       put_test_config(environment_name: "test", traces_sample_rate: 0.5)