diff --git a/Cargo.lock b/Cargo.lock
index 99009e7e1..350c7732a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -7411,8 +7411,11 @@ version = "0.1.0"
 dependencies = [
  "prost",
  "rand",
+ "serde",
+ "serde_json",
  "thiserror 2.0.6",
  "tonic",
+ "tracing",
  "xmtp_common",
  "xmtp_proto",
 ]
diff --git a/xmtp_content_types/Cargo.toml b/xmtp_content_types/Cargo.toml
index 2b7c506d1..82a8f5eac 100644
--- a/xmtp_content_types/Cargo.toml
+++ b/xmtp_content_types/Cargo.toml
@@ -8,6 +8,9 @@ license.workspace = true
 thiserror = { workspace = true }
 prost = { workspace = true, features = ["prost-derive"] }
 rand = { workspace = true }
+serde = { workspace = true, features = ["derive"] }
+serde_json = { workspace = true }
+tracing.workspace = true
 
 # XMTP/Local
 xmtp_proto = { workspace = true, features = ["convert"] }
diff --git a/xmtp_content_types/src/reaction.rs b/xmtp_content_types/src/reaction.rs
index f70b925bc..fafe99c4a 100644
--- a/xmtp_content_types/src/reaction.rs
+++ b/xmtp_content_types/src/reaction.rs
@@ -3,6 +3,7 @@ use std::collections::HashMap;
 use crate::{CodecError, ContentCodec};
 use prost::Message;
 
+use serde::{Deserialize, Serialize};
 use xmtp_proto::xmtp::mls::message_contents::{
     content_types::ReactionV2, ContentTypeId, EncodedContent,
 };
@@ -47,6 +48,42 @@ impl ContentCodec<ReactionV2> for ReactionCodec {
     }
 }
 
+// JSON format for legacy reaction is defined here: https://github.com/xmtp/xmtp-js/blob/main/content-types/content-type-reaction/src/Reaction.ts
+#[derive(Debug, Serialize, Deserialize)]
+pub struct LegacyReaction {
+    /// The message ID for the message that is being reacted to
+    pub reference: String,
+    /// The inbox ID of the user who sent the message that is being reacted to
+    #[serde(rename = "referenceInboxId", skip_serializing_if = "Option::is_none")]
+    pub reference_inbox_id: Option<String>,
+    /// The action of the reaction ("added" or "removed")
+    pub action: String,
+    /// The content of the reaction
+    pub content: String,
+    /// The schema of the content ("unicode", "shortcode", or "custom")
+    pub schema: String,
+}
+
+impl LegacyReaction {
+    pub fn decode(content: &[u8]) -> Option<LegacyReaction> {
+        // Try to decode the content as UTF-8 string first
+        if let Ok(decoded_content) = String::from_utf8(content.to_vec()) {
+            tracing::info!(
+                "attempting legacy json deserialization: {}",
+                decoded_content
+            );
+            // Try parsing as canonical JSON format
+            if let Ok(reaction) = serde_json::from_str::<LegacyReaction>(&decoded_content) {
+                return Some(reaction);
+            }
+            tracing::error!("legacy json deserialization failed");
+        } else {
+            tracing::error!("utf-8 deserialization failed");
+        }
+        None
+    }
+}
+
 #[cfg(test)]
 pub(crate) mod tests {
     #[cfg(target_arch = "wasm32")]
@@ -56,6 +93,7 @@ pub(crate) mod tests {
         ReactionAction, ReactionSchema, ReactionV2,
     };
 
+    use serde_json::json;
     use xmtp_common::rand_string;
 
     use super::*;
@@ -80,4 +118,27 @@ pub(crate) mod tests {
         assert_eq!(decoded.content, "👍".to_string());
         assert_eq!(decoded.schema, ReactionSchema::Unicode as i32);
     }
+
+    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
+    #[cfg_attr(not(target_arch = "wasm32"), test)]
+    fn test_legacy_reaction_deserialization() {
+        let reference = "0123456789abcdef";
+        let legacy_json = json!({
+            "reference": reference,
+            "referenceInboxId": "some_inbox_id",
+            "action": "added",
+            "content": "👍",
+            "schema": "unicode"
+        });
+
+        let content = legacy_json.to_string().into_bytes();
+        let decoded_reference: String = LegacyReaction::decode(&content).unwrap().reference;
+
+        assert_eq!(decoded_reference, reference);
+
+        // Test invalid JSON
+        let invalid_content = b"invalid json";
+        let failed_decode = LegacyReaction::decode(invalid_content);
+        assert!(failed_decode.is_none());
+    }
 }
diff --git a/xmtp_mls/src/groups/mod.rs b/xmtp_mls/src/groups/mod.rs
index b72a18eb2..7b1ea9477 100644
--- a/xmtp_mls/src/groups/mod.rs
+++ b/xmtp_mls/src/groups/mod.rs
@@ -36,7 +36,7 @@ use openmls_traits::OpenMlsProvider;
 use prost::Message;
 use thiserror::Error;
 use tokio::sync::Mutex;
-use xmtp_content_types::reaction::ReactionCodec;
+use xmtp_content_types::reaction::{LegacyReaction, ReactionCodec};
 
 use self::device_sync::DeviceSyncError;
 pub use self::group_permissions::PreconfiguredPolicies;
@@ -348,13 +348,12 @@ impl TryFrom<EncodedContent> for QueryableContentFields {
             content_type_id.version_major,
         ) {
             (ReactionCodec::TYPE_ID, major) if major >= 2 => {
-                let reaction = ReactionV2::decode(content.content.as_slice())?;
-                hex::decode(reaction.reference).ok()
-            }
-            (ReactionCodec::TYPE_ID, _) => {
-                // TODO: Implement JSON deserialization for legacy reaction format
-                None
+                ReactionV2::decode(content.content.as_slice())
+                    .ok()
+                    .and_then(|reaction| hex::decode(reaction.reference).ok())
             }
+            (ReactionCodec::TYPE_ID, _) => LegacyReaction::decode(&content.content)
+                .and_then(|legacy_reaction| hex::decode(legacy_reaction.reference).ok()),
             _ => None,
         };
 
@@ -796,7 +795,9 @@ impl<ScopedClient: ScopedGroupClient> MlsGroup<ScopedClient> {
     fn extract_queryable_content_fields(message: &[u8]) -> QueryableContentFields {
         // Return early with default if decoding fails or type is missing
         EncodedContent::decode(message)
-            .inspect_err(|e| tracing::debug!("Failed to decode message as EncodedContent: {}", e))
+            .inspect_err(|_| {
+                tracing::debug!("No queryable content fields, msg not formatted as encoded content")
+            })
             .and_then(|content| {
                 QueryableContentFields::try_from(content).inspect_err(|e| {
                     tracing::debug!(