diff --git a/Cargo.lock b/Cargo.lock
index 900761b1..50f4efbf 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2255,6 +2255,25 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "rmp"
+version = "0.8.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ba8be72d372b2c9b35542551678538b562e7cf86c3315773cae48dfbfe7790c"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "rmp-serde"
+version = "1.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72f81bee8c8ef9b577d1681a70ebbc962c232461e397b22c208c43c04b67a155"
+dependencies = [
+ "rmp",
+ "serde",
+]
+
 [[package]]
 name = "rsa"
 version = "0.9.10"
@@ -2991,6 +3010,7 @@ dependencies = [
  "prost-types",
  "rand 0.8.5",
  "rdkafka",
+ "rmp-serde",
  "rstest",
  "sentry",
  "sentry_protos",
diff --git a/Cargo.toml b/Cargo.toml
index 1ad2b992..c2e0bd92 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,6 +31,7 @@ prost = "0.14"
 prost-types = "0.14"
 rand = "0.8.5"
 rdkafka = { version = "0.37.0", features = ["cmake-build", "ssl"] }
+rmp-serde = "1.3"
 sentry = { version = "0.41.0", default-features = false, features = [
     # default features, except `release-health` is disabled
     "backtrace",
diff --git a/src/config.rs b/src/config.rs
index 523c0286..fcee5fb9 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -301,6 +301,22 @@ pub struct Config {
 
     /// Maps every application to its worker endpoint, both represented as strings.
     pub worker_map: BTreeMap<String, String>,
+
+    /// Enable passthrough mode for consuming raw bytes from legacy topics.
+    /// In passthrough mode, raw Kafka message bytes are wrapped into TaskActivation.
+    pub passthrough_mode: bool,
+
+    /// The namespace to assign to passthrough activations.
+    pub passthrough_namespace: Option<String>,
+
+    /// The application to assign to passthrough activations.
+    pub passthrough_application: Option<String>,
+
+    /// The taskname to assign to passthrough activations.
+    pub passthrough_taskname: Option<String>,
+
+    /// Processing deadline duration in seconds for passthrough activations.
+    pub passthrough_processing_deadline_duration: u64,
 }
 
 impl Default for Config {
@@ -386,6 +402,11 @@ impl Default for Config {
             callback_addr: "0.0.0.0".into(),
             callback_port: 50051,
             worker_map: [("sentry".into(), "http://127.0.0.1:50052".into())].into(),
+            passthrough_mode: false,
+            passthrough_namespace: None,
+            passthrough_application: None,
+            passthrough_taskname: None,
+            passthrough_processing_deadline_duration: 30,
         }
     }
 }
diff --git a/src/kafka/deserialize.rs b/src/kafka/deserialize.rs
new file mode 100644
index 00000000..7e650b27
--- /dev/null
+++ b/src/kafka/deserialize.rs
@@ -0,0 +1,42 @@
+use std::sync::Arc;
+
+use anyhow::Error;
+use rdkafka::message::OwnedMessage;
+
+use crate::config::Config;
+use crate::store::activation::InflightActivation;
+
+use super::deserialize_activation::{self, DeserializeActivationConfig};
+use super::deserialize_passthrough::{self, PassthroughConfig};
+
+pub struct DeserializeConfig {
+    activation_config: DeserializeActivationConfig,
+    passthrough_config: Option<PassthroughConfig>,
+}
+
+impl DeserializeConfig {
+    pub fn from_config(config: &Config) -> Self {
+        Self {
+            activation_config: DeserializeActivationConfig::from_config(config),
+            passthrough_config: PassthroughConfig::from_config(config),
+        }
+    }
+}
+
+/// Create a unified deserializer that handles both normal and passthrough modes.
+/// In passthrough mode, raw Kafka bytes are wrapped into a TaskActivation.
+/// In normal mode, Kafka messages are expected to contain encoded TaskActivation protos.
+pub fn new(
+    config: DeserializeConfig,
+) -> impl Fn(Arc<OwnedMessage>) -> Result<InflightActivation, Error> {
+    let passthrough_deserializer = config.passthrough_config.map(deserialize_passthrough::new);
+    let activation_deserializer = deserialize_activation::new(config.activation_config);
+
+    move |msg: Arc<OwnedMessage>| {
+        if let Some(ref pt_deserializer) = passthrough_deserializer {
+            pt_deserializer(msg)
+        } else {
+            activation_deserializer(msg)
+        }
+    }
+}
diff --git a/src/kafka/deserialize_passthrough.rs b/src/kafka/deserialize_passthrough.rs
new file mode 100644
index 00000000..3d270994
--- /dev/null
+++ b/src/kafka/deserialize_passthrough.rs
@@ -0,0 +1,227 @@
+use std::collections::HashMap;
+use std::sync::Arc;
+
+use anyhow::{Error, anyhow};
+use chrono::Utc;
+use prost::Message as _;
+use rdkafka::Message;
+use rdkafka::message::OwnedMessage;
+use sentry_protos::taskbroker::v1::{OnAttemptsExceeded, TaskActivation};
+use uuid::Uuid;
+
+use crate::config::Config;
+use crate::store::activation::{InflightActivation, InflightActivationStatus};
+
+use super::deserialize_activation::bucket_from_id;
+
+pub struct PassthroughConfig {
+    pub namespace: String,
+    pub application: String,
+    pub taskname: String,
+    pub processing_deadline_duration: u64,
+}
+
+impl PassthroughConfig {
+    pub fn from_config(config: &Config) -> Option<Self> {
+        if !config.passthrough_mode {
+            return None;
+        }
+        Some(Self {
+            namespace: config
+                .passthrough_namespace
+                .clone()
+                .expect("passthrough_namespace required when passthrough_mode is enabled"),
+            application: config
+                .passthrough_application
+                .clone()
+                .expect("passthrough_application required when passthrough_mode is enabled"),
+            taskname: config
+                .passthrough_taskname
+                .clone()
+                .expect("passthrough_taskname required when passthrough_mode is enabled"),
+            processing_deadline_duration: config.passthrough_processing_deadline_duration,
+        })
+    }
+}
+
+/// Encode raw bytes into msgpack format: {"args": [raw_bytes], "kwargs": {}}
+fn encode_passthrough_params(raw_bytes: &[u8]) -> Result<Vec<u8>, Error> {
+    use serde::Serialize;
+
+    #[derive(Serialize)]
+    struct Params<'a> {
+        args: (&'a [u8],),
+        kwargs: HashMap<(), ()>,
+    }
+
+    let params = Params {
+        args: (raw_bytes,),
+        kwargs: HashMap::new(),
+    };
+
+    rmp_serde::to_vec_named(&params).map_err(|e| anyhow!("Failed to encode msgpack: {}", e))
+}
+
+/// Create a deserializer closure for passthrough mode.
+/// Wraps raw Kafka message bytes into a TaskActivation with msgpack-encoded parameters_bytes.
+pub fn new(
+    config: PassthroughConfig,
+) -> impl Fn(Arc<OwnedMessage>) -> Result<InflightActivation, Error> {
+    move |msg: Arc<OwnedMessage>| {
+        let Some(payload) = msg.payload() else {
+            return Err(anyhow!("Message has no payload"));
+        };
+
+        let id = Uuid::new_v4().to_string();
+        let parameters_bytes = encode_passthrough_params(payload)?;
+        let now = Utc::now();
+        let received_at = prost_types::Timestamp {
+            seconds: now.timestamp(),
+            nanos: 0,
+        };
+
+        let activation = TaskActivation {
+            id: id.clone(),
+            application: Some(config.application.clone()),
+            namespace: config.namespace.clone(),
+            taskname: config.taskname.clone(),
+            #[allow(deprecated)]
+            parameters: String::new(),
+            parameters_bytes,
+            headers: HashMap::new(),
+            received_at: Some(received_at),
+            retry_state: None,
+            processing_deadline_duration: config.processing_deadline_duration,
+            expires: None,
+            delay: None,
+        };
+
+        let activation_bytes = activation.encode_to_vec();
+        let bucket = bucket_from_id(&id);
+
+        metrics::histogram!(
+            "consumer.passthrough.payload_size_bytes",
+            "namespace" => config.namespace.clone(),
+            "taskname" => config.taskname.clone()
+        )
+        .record(payload.len() as f64);
+
+        Ok(InflightActivation {
+            id,
+            activation: activation_bytes,
+            status: InflightActivationStatus::Pending,
+            partition: msg.partition(),
+            offset: msg.offset(),
+            added_at: now,
+            received_at: now,
+            processing_deadline: None,
+            claim_expires_at: None,
+            processing_deadline_duration: config.processing_deadline_duration as i32,
+            processing_attempts: 0,
+            expires_at: None,
+            delay_until: None,
+            at_most_once: false,
+            application: config.application.clone(),
+            namespace: config.namespace.clone(),
+            taskname: config.taskname.clone(),
+            on_attempts_exceeded: OnAttemptsExceeded::Discard,
+            bucket,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::sync::Arc;
+
+    use rdkafka::Timestamp;
+    use rdkafka::message::OwnedMessage;
+
+    use super::*;
+
+    #[test]
+    fn test_encode_passthrough_params() {
+        use serde::Deserialize;
+
+        #[derive(Deserialize, Debug)]
+        struct Params {
+            args: (Vec<u8>,),
+            kwargs: HashMap<(), ()>,
+        }
+
+        let raw_bytes = b"hello world";
+        let encoded = encode_passthrough_params(raw_bytes).unwrap();
+
+        // Decode and verify
+        let decoded: Params = rmp_serde::from_slice(&encoded).unwrap();
+        assert_eq!(decoded.args.0, raw_bytes);
+        assert!(decoded.kwargs.is_empty());
+    }
+
+    #[test]
+    fn test_passthrough_deserializer() {
+        let config = PassthroughConfig {
+            namespace: "test-namespace".to_string(),
+            application: "test-app".to_string(),
+            taskname: "test-task".to_string(),
+            processing_deadline_duration: 60,
+        };
+
+        let deserializer = new(config);
+
+        let raw_payload = b"raw kafka message bytes";
+        let message = OwnedMessage::new(
+            Some(raw_payload.to_vec()),
+            None,
+            "legacy-topic".into(),
+            Timestamp::now(),
+            0,
+            42,
+            None,
+        );
+
+        let result = deserializer(Arc::new(message));
+        assert!(result.is_ok());
+
+        let inflight = result.unwrap();
+        assert_eq!(inflight.namespace, "test-namespace");
+        assert_eq!(inflight.application, "test-app");
+        assert_eq!(inflight.taskname, "test-task");
+        assert_eq!(inflight.processing_deadline_duration, 60);
+        assert_eq!(inflight.offset, 42);
+        assert_eq!(inflight.status, InflightActivationStatus::Pending);
+
+        // Verify the activation can be decoded
+        let activation = TaskActivation::decode(inflight.activation.as_slice()).unwrap();
+        assert_eq!(activation.namespace, "test-namespace");
+        assert_eq!(activation.application, Some("test-app".to_string()));
+        assert_eq!(activation.taskname, "test-task");
+        assert!(!activation.parameters_bytes.is_empty());
+    }
+
+    #[test]
+    fn test_passthrough_deserializer_empty_payload() {
+        let config = PassthroughConfig {
+            namespace: "test-namespace".to_string(),
+            application: "test-app".to_string(),
+            taskname: "test-task".to_string(),
+            processing_deadline_duration: 60,
+        };
+
+        let deserializer = new(config);
+
+        let message = OwnedMessage::new(
+            None, // No payload
+            None,
+            "legacy-topic".into(),
+            Timestamp::now(),
+            0,
+            0,
+            None,
+        );
+
+        let result = deserializer(Arc::new(message));
+        assert!(result.is_err());
+        assert!(result.unwrap_err().to_string().contains("no payload"));
+    }
+}
diff --git a/src/kafka/mod.rs b/src/kafka/mod.rs
index ae4122ac..87b8c156 100644
--- a/src/kafka/mod.rs
+++ b/src/kafka/mod.rs
@@ -1,6 +1,8 @@
 pub mod admin;
 pub mod consumer;
+pub mod deserialize;
 pub mod deserialize_activation;
+pub mod deserialize_passthrough;
 pub mod inflight_activation_batcher;
 pub mod inflight_activation_writer;
 pub mod os_stream_writer;
diff --git a/src/main.rs b/src/main.rs
index 4c174420..c91a766f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -20,8 +20,7 @@ use taskbroker::grpc::metrics_middleware::MetricsLayer;
 use taskbroker::grpc::server::TaskbrokerServer;
 use taskbroker::kafka::admin::create_missing_topics;
 use taskbroker::kafka::consumer::start_consumer;
-use taskbroker::kafka::deserialize_activation;
-use taskbroker::kafka::deserialize_activation::DeserializeActivationConfig;
+use taskbroker::kafka::deserialize::{self, DeserializeConfig};
 use taskbroker::kafka::inflight_activation_batcher::{
     ActivationBatcherConfig, InflightActivationBatcher,
 };
@@ -174,7 +173,7 @@ async fn main() -> Result<(), Error> {
                         ),
 
                     map:
-                        deserialize_activation::new(DeserializeActivationConfig::from_config(&consumer_config)),
+                        deserialize::new(DeserializeConfig::from_config(&consumer_config)),
 
                     reduce:
                         InflightActivationBatcher::new(