diff --git a/spdlog/Cargo.toml b/spdlog/Cargo.toml
index 7458628..f698a1a 100644
--- a/spdlog/Cargo.toml
+++ b/spdlog/Cargo.toml
@@ -37,7 +37,7 @@ native = []
 libsystemd = ["libsystemd-sys"]
 multi-thread = ["crossbeam"]
 runtime-pattern = ["spdlog-internal"]
-serde_json = ["serde", "dep:serde_json"]
+serde_json = ["serde", "dep:serde_json", "value-bag/serde1"]
 
 [dependencies]
 arc-swap = "1.5.1"
diff --git a/spdlog/src/formatter/full_formatter.rs b/spdlog/src/formatter/full_formatter.rs
index 97dc37a..125d81b 100644
--- a/spdlog/src/formatter/full_formatter.rs
+++ b/spdlog/src/formatter/full_formatter.rs
@@ -62,14 +62,18 @@ impl FullFormatter {
             }
         }
 
-        fmt_with_time(ctx, record, |mut time: TimeDate| {
-            dest.write_str("[")?;
-            dest.write_str(time.full_second_str())?;
-            dest.write_str(".")?;
-            write!(dest, "{:03}", time.millisecond())?;
-            dest.write_str("] [")?;
-            Ok(())
-        })?;
+        fmt_with_time(
+            ctx,
+            record,
+            |mut time: TimeDate| -> Result<(), fmt::Error> {
+                dest.write_str("[")?;
+                dest.write_str(time.full_second_str())?;
+                dest.write_str(".")?;
+                write!(dest, "{:03}", time.millisecond())?;
+                dest.write_str("] [")?;
+                Ok(())
+            },
+        )?;
 
         if let Some(logger_name) = record.logger_name() {
             dest.write_str(logger_name)?;
diff --git a/spdlog/src/formatter/json_formatter.rs b/spdlog/src/formatter/json_formatter.rs
index 82238f0..5a94dc1 100644
--- a/spdlog/src/formatter/json_formatter.rs
+++ b/spdlog/src/formatter/json_formatter.rs
@@ -5,7 +5,10 @@ use std::{
 };
 
 use cfg_if::cfg_if;
-use serde::{ser::SerializeStruct, Serialize};
+use serde::{
+    ser::{SerializeMap, SerializeStruct},
+    Serialize, Serializer,
+};
 
 use crate::{
     formatter::{Formatter, FormatterContext},
@@ -21,7 +24,7 @@ struct JsonRecord<'a>(&'a Record<'a>);
 impl Serialize for JsonRecord<'_> {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
-        S: serde::Serializer,
+        S: Serializer,
     {
         let fields_len =
             4 + opt_to_num(self.0.logger_name()) + opt_to_num(self.0.source_location());
@@ -40,6 +43,11 @@ impl Serialize for JsonRecord<'_> {
                 .expect("invalid timestamp"),
         )?;
         record.serialize_field("payload", self.0.payload())?;
+
+        if !self.0.key_values().is_empty() {
+            record.serialize_field("kv", &JsonKV(&self.0))?;
+        }
+
         if let Some(logger_name) = self.0.logger_name() {
             record.serialize_field("logger", logger_name)?;
         }
@@ -52,6 +60,22 @@ impl Serialize for JsonRecord<'_> {
     }
 }
 
+struct JsonKV<'a>(&'a Record<'a>);
+
+impl<'a> Serialize for JsonKV<'a> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let kv = self.0.key_values();
+        let mut map = serializer.serialize_map(Some(kv.len()))?;
+        for (key, value) in kv {
+            map.serialize_entry(key.as_str(), &value)?;
+        }
+        map.end()
+    }
+}
+
 impl<'a> From<&'a Record<'a>> for JsonRecord<'a> {
     fn from(value: &'a Record<'a>) -> Self {
         JsonRecord(value)
@@ -96,6 +120,7 @@ impl From<JsonFormatterError> for crate::Error {
 /// | `level`     | String       | The level of the log. Same as the return of [`Level::as_str`].                                                                 |
 /// | `timestamp` | Integer(u64) | The timestamp when the log was generated, in milliseconds since January 1, 1970 00:00:00 UTC.                                  |
 /// | `payload`   | String       | The contents of the log.                                                                                                       |
+/// | `kv`        | Object/Null  | The key-values of the log. Null if kv is not specified.                                                                        |
 /// | `logger`    | String/Null  | The name of the logger. Null if the logger has no name.                                                                        |
 /// | `tid`       | Integer(u64) | The thread ID when the log was generated.                                                                                      |
 /// | `source`    | Object/Null  | The source location of the log. See [`SourceLocation`] for its schema. Null if crate feature `source-location` is not enabled. |
@@ -126,6 +151,13 @@ impl From<JsonFormatterError> for crate::Error {
 ///    {"level":"error","timestamp":1722817541459,"payload":"something went wrong","logger":"app-component","tid":3478045}
 ///    ```
 /// 
+///  - If key-values are present:
+/// 
+///    ```json
+///    {"level":"info","timestamp":1722817541459,"payload":"hello, world!","kv":{"k1":123,"k2":"cool"},"tid":3478045}
+///    {"level":"error","timestamp":1722817541459,"payload":"something went wrong","kv":{"k1":123,"k2":"cool"},"tid":3478045}
+///    ```
+/// 
 ///  - If crate feature `source-location` is enabled:
 /// 
 ///    ```json
@@ -193,7 +225,7 @@ mod tests {
     use chrono::prelude::*;
 
     use super::*;
-    use crate::{Level, SourceLocation, __EOL};
+    use crate::{kv, Level, SourceLocation, __EOL};
 
     #[test]
     fn should_format_json() {
@@ -269,4 +301,31 @@ mod tests {
             )
         );
     }
+
+    #[test]
+    fn should_format_json_with_kv() {
+        let mut dest = StringBuf::new();
+        let formatter = JsonFormatter::new();
+        let kvs = [
+            (kv::Key::__from_static_str("k1"), kv::Value::from(114)),
+            (kv::Key::__from_static_str("k2"), kv::Value::from("514")),
+        ];
+        let record = Record::new(Level::Info, "payload", None, None, &kvs);
+        let mut ctx = FormatterContext::new();
+        formatter.format(&record, &mut dest, &mut ctx).unwrap();
+
+        let local_time: DateTime<Local> = record.time().into();
+
+        assert_eq!(ctx.style_range(), None);
+        assert_eq!(
+            dest.to_string(),
+            format!(
+                r#"{{"level":"info","timestamp":{},"payload":"{}","kv":{{"k1":114,"k2":"514"}},"tid":{}}}{}"#,
+                local_time.timestamp_millis(),
+                "payload",
+                record.tid(),
+                __EOL
+            )
+        );
+    }
 }