diff --git a/kotlin-sdk-server/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StreamableHttpServerTransport.kt b/kotlin-sdk-server/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StreamableHttpServerTransport.kt
index dcba84873..465f70fe3 100644
--- a/kotlin-sdk-server/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StreamableHttpServerTransport.kt
+++ b/kotlin-sdk-server/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StreamableHttpServerTransport.kt
@@ -34,6 +34,7 @@ import io.modelcontextprotocol.kotlin.sdk.types.SUPPORTED_PROTOCOL_VERSIONS
 import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.NonCancellable
 import kotlinx.coroutines.awaitCancellation
+import kotlinx.coroutines.currentCoroutineContext
 import kotlinx.coroutines.job
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
@@ -375,9 +376,13 @@ public class StreamableHttpServerTransport(private val configuration: Configurat
     }
 
     override suspend fun close() {
+        val currentJob = currentCoroutineContext().job
         withContext(NonCancellable) {
             streamMutex.withLock {
                 streamsMapping.values.forEach {
+                    if (it.call.coroutineContext.job !== currentJob) {
+                        it.call.coroutineContext.job.cancel()
+                    }
                     try {
                         it.session?.close()
                     } catch (_: Exception) {
@@ -611,12 +616,16 @@ public class StreamableHttpServerTransport(private val configuration: Configurat
         // SSE headers (Content-Type, Cache-Control, Connection) are already set by the framework's SSE handler
         flushSse(sseSession)
         val newContext = SessionContext(sseSession, call)
+        val currentJob = currentCoroutineContext().job
         streamMutex.withLock {
             streamsMapping[STANDALONE_SSE_STREAM_ID]?.let { existingContext ->
                 // Close the previous SSE session. If alive, this cancels the old
                 // coroutine (which will hit its identity-guarded finally — that finally
                 // won't double-remove, since we replace the mapping below).
                 try {
+                    if (existingContext.call.coroutineContext.job !== currentJob) {
+                        existingContext.call.coroutineContext.job.cancel()
+                    }
                     existingContext.session?.close()
                 } catch (e: CancellationException) {
                     throw e
@@ -660,9 +669,13 @@ public class StreamableHttpServerTransport(private val configuration: Configurat
         if (configuration.enableJsonResponse) return
         val streamId = requestToStreamMapping[requestId] ?: return
         val sessionContext = streamsMapping[streamId] ?: return
+        val currentJob = currentCoroutineContext().job
 
         withContext(NonCancellable) {
             try {
+                if (sessionContext.call.coroutineContext.job !== currentJob) {
+                    sessionContext.call.coroutineContext.job.cancel()
+                }
                 sessionContext.session?.close()
             } catch (e: Exception) {
                 _onError(e)
diff --git a/kotlin-sdk-server/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StreamableHttpServerTransportTest.kt b/kotlin-sdk-server/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StreamableHttpServerTransportTest.kt
index 43ff6051e..74a2a8e90 100644
--- a/kotlin-sdk-server/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StreamableHttpServerTransportTest.kt
+++ b/kotlin-sdk-server/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StreamableHttpServerTransportTest.kt
@@ -16,12 +16,14 @@ import io.ktor.client.request.prepareGet
 import io.ktor.client.request.setBody
 import io.ktor.client.statement.bodyAsChannel
 import io.ktor.http.ContentType
+import io.ktor.http.Headers
 import io.ktor.http.HttpHeaders
 import io.ktor.http.HttpStatusCode
 import io.ktor.http.contentType
 import io.ktor.serialization.kotlinx.json.json
 import io.ktor.server.application.ApplicationCall
 import io.ktor.server.application.install
+import io.ktor.server.request.ApplicationRequest
 import io.ktor.server.routing.get
 import io.ktor.server.routing.post
 import io.ktor.server.routing.routing
@@ -32,6 +34,8 @@ import io.ktor.sse.ServerSentEvent
 import io.ktor.utils.io.ByteReadChannel
 import io.ktor.utils.io.readLine
 import io.ktor.utils.io.readUTF8Line
+import io.mockk.every
+import io.mockk.mockk
 import io.modelcontextprotocol.kotlin.sdk.types.CancelledNotification
 import io.modelcontextprotocol.kotlin.sdk.types.CancelledNotificationParams
 import io.modelcontextprotocol.kotlin.sdk.types.ClientCapabilities
@@ -64,6 +68,7 @@ import kotlinx.coroutines.cancel
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.withContext
 import kotlinx.coroutines.withTimeout
 import kotlinx.serialization.builtins.ListSerializer
 import kotlinx.serialization.json.buildJsonObject
@@ -1065,6 +1070,64 @@ class StreamableHttpServerTransportTest {
         }
     }
 
+    @Test
+    fun `closing transport cancels standalone GET SSE request`() = runTest {
+        val callJob = SupervisorJob()
+        val callContext = callJob + Dispatchers.Default
+        val call = mockk<ApplicationCall>(relaxed = true)
+        val request = mockk<ApplicationRequest>(relaxed = true)
+        val requestHeaders = Headers.build {
+            append(HttpHeaders.Accept, ContentType.Text.EventStream.toString())
+            append("mcp-protocol-version", LATEST_PROTOCOL_VERSION)
+        }
+        every { call.coroutineContext } returns callContext
+        every { call.request } returns request
+        every { request.headers } returns requestHeaders
+
+        val mappingRegistered = CompletableDeferred<Unit>()
+        val session = FakeServerSSESession(call, callContext)
+        val transport = StreamableHttpServerTransport(
+            StreamableHttpServerTransport.Configuration(
+                eventStore = object : EventStore {
+                    override suspend fun storeEvent(streamId: String, message: JSONRPCMessage): String {
+                        mappingRegistered.complete(Unit)
+                        return "priming-event"
+                    }
+
+                    override suspend fun replayEventsAfter(
+                        lastEventId: String,
+                        sender: suspend (eventId: String, message: JSONRPCMessage) -> Unit,
+                    ): String = "standalone-stream"
+
+                    override suspend fun getStreamIdForEventId(eventId: String): String? = null
+                },
+            ),
+        )
+        transport.setSessionIdGenerator(null)
+
+        val handler = CoroutineScope(callContext).launch {
+            transport.handleGetRequest(session, call)
+        }
+
+        try {
+            withContext(Dispatchers.Default) {
+                withTimeout(5.seconds) { mappingRegistered.await() }
+            }
+
+            transport.close()
+            assertTrue(callJob.isCancelled)
+
+            withContext(Dispatchers.Default) {
+                withTimeout(5.seconds) { handler.join() }
+            }
+            assertFalse(handler.isActive)
+        } finally {
+            callJob.cancel()
+            handler.cancel()
+            transport.close()
+        }
+    }
+
     @Test
     fun `GET SSE reconnect after previous stream disconnects should succeed`() = testApplication {
         val mcpPath = "/mcp"