diff --git a/examples/Cargo.toml b/examples/Cargo.toml
index d6cf6e356d..66e1e2d47e 100644
--- a/examples/Cargo.toml
+++ b/examples/Cargo.toml
@@ -10,7 +10,7 @@ futures = "0.3.6"
 openssl = "0.10.32"
 rustyline = "9"
 rustyline-derive = "0.6"
-scylla = {path = "../scylla", features = ["ssl", "cloud", "chrono", "time", "num-bigint-03"]}
+scylla = {path = "../scylla", features = ["ssl", "cloud", "chrono", "time", "num-bigint-03", "num-bigint-04"]}
 tokio = {version = "1.1.0", features = ["full"]}
 tracing = "0.1.25"
 tracing-subscriber = { version = "0.3.14", features = ["env-filter"] }
diff --git a/scylla-cql/Cargo.toml b/scylla-cql/Cargo.toml
index a298888164..76adedcb91 100644
--- a/scylla-cql/Cargo.toml
+++ b/scylla-cql/Cargo.toml
@@ -21,6 +21,7 @@ uuid = "1.0"
 thiserror = "1.0"
 bigdecimal = "0.2.0"
 num-bigint-03 = { package = "num-bigint", version = "0.3", optional = true }
+num-bigint-04 = { package = "num-bigint", version = "0.4", optional = true }
 chrono = { version = "0.4.27", default-features = false, optional = true }
 lz4_flex = { version = "0.11.1" }
 async-trait = "0.1.57"
@@ -41,4 +42,5 @@ secret = ["secrecy"]
 time = ["dep:time"]
 chrono = ["dep:chrono"]
 num-bigint-03 = ["dep:num-bigint-03"]
-full-serialization = ["chrono", "time", "secret", "num-bigint-03"]
+num-bigint-04 = ["dep:num-bigint-04"]
+full-serialization = ["chrono", "time", "secret", "num-bigint-03", "num-bigint-04"]
diff --git a/scylla-cql/src/frame/response/cql_to_rust.rs b/scylla-cql/src/frame/response/cql_to_rust.rs
index ba40b88f98..44da95097f 100644
--- a/scylla-cql/src/frame/response/cql_to_rust.rs
+++ b/scylla-cql/src/frame/response/cql_to_rust.rs
@@ -156,6 +156,16 @@ impl FromCqlVal<CqlValue> for num_bigint_03::BigInt {
     }
 }
 
+#[cfg(feature = "num-bigint-04")]
+impl FromCqlVal<CqlValue> for num_bigint_04::BigInt {
+    fn from_cql(cql_val: CqlValue) -> Result<Self, FromCqlValError> {
+        match cql_val {
+            CqlValue::Varint(cql_varint) => Ok(cql_varint.into()),
+            _ => Err(FromCqlValError::BadCqlType),
+        }
+    }
+}
+
 #[cfg(feature = "chrono")]
 impl FromCqlVal<CqlValue> for NaiveDate {
     fn from_cql(cql_val: CqlValue) -> Result<Self, FromCqlValError> {
@@ -467,7 +477,7 @@ mod tests {
 
     #[cfg(feature = "num-bigint-03")]
     #[test]
-    fn varint_from_cql() {
+    fn varint03_from_cql() {
         use num_bigint_03::ToBigInt;
 
         let big_int = 0.to_bigint().unwrap();
@@ -477,6 +487,18 @@ mod tests {
         );
     }
 
+    #[cfg(feature = "num-bigint-04")]
+    #[test]
+    fn varint04_from_cql() {
+        use num_bigint_04::ToBigInt;
+
+        let big_int = 0.to_bigint().unwrap();
+        assert_eq!(
+            Ok(big_int),
+            num_bigint_04::BigInt::from_cql(CqlValue::Varint(0.to_bigint().unwrap().into()))
+        );
+    }
+
     #[test]
     fn decimal_from_cql() {
         let decimal = BigDecimal::from_str("123.4").unwrap();
diff --git a/scylla-cql/src/frame/response/result.rs b/scylla-cql/src/frame/response/result.rs
index 813661b37a..834654ee94 100644
--- a/scylla-cql/src/frame/response/result.rs
+++ b/scylla-cql/src/frame/response/result.rs
@@ -1025,16 +1025,14 @@ mod tests {
         assert_eq!(double_serialize, CqlValue::Double(double));
     }
 
-    #[cfg(feature = "num-bigint-03")]
-    #[test]
-    fn test_varint() {
-        use num_bigint_03::ToBigInt;
-
-        struct Test<'a> {
-            value: num_bigint_03::BigInt,
-            encoding: &'a [u8],
-        }
+    #[cfg(any(feature = "num-bigint-03", feature = "num-bigint-04"))]
+    struct VarintTestCase {
+        value: i32,
+        encoding: Vec<u8>,
+    }
 
+    #[cfg(any(feature = "num-bigint-03", feature = "num-bigint-04"))]
+    fn varint_test_cases_from_spec() -> Vec<VarintTestCase> {
         /*
             Table taken from CQL Binary Protocol v4 spec
 
@@ -1049,44 +1047,65 @@ mod tests {
              -128 |     0x80
              -129 |   0xFF7F
         */
-        let tests = [
-            Test {
-                value: 0.to_bigint().unwrap(),
-                encoding: &[0x00],
+        vec![
+            VarintTestCase {
+                value: 0,
+                encoding: vec![0x00],
             },
-            Test {
-                value: 1.to_bigint().unwrap(),
-                encoding: &[0x01],
+            VarintTestCase {
+                value: 1,
+                encoding: vec![0x01],
             },
-            Test {
-                value: 127.to_bigint().unwrap(),
-                encoding: &[0x7F],
+            VarintTestCase {
+                value: 127,
+                encoding: vec![0x7F],
             },
-            Test {
-                value: 128.to_bigint().unwrap(),
-                encoding: &[0x00, 0x80],
+            VarintTestCase {
+                value: 128,
+                encoding: vec![0x00, 0x80],
             },
-            Test {
-                value: 129.to_bigint().unwrap(),
-                encoding: &[0x00, 0x81],
+            VarintTestCase {
+                value: 129,
+                encoding: vec![0x00, 0x81],
             },
-            Test {
-                value: (-1).to_bigint().unwrap(),
-                encoding: &[0xFF],
+            VarintTestCase {
+                value: -1,
+                encoding: vec![0xFF],
             },
-            Test {
-                value: (-128).to_bigint().unwrap(),
-                encoding: &[0x80],
+            VarintTestCase {
+                value: -128,
+                encoding: vec![0x80],
             },
-            Test {
-                value: (-129).to_bigint().unwrap(),
-                encoding: &[0xFF, 0x7F],
+            VarintTestCase {
+                value: -129,
+                encoding: vec![0xFF, 0x7F],
             },
-        ];
+        ]
+    }
+
+    #[cfg(feature = "num-bigint-03")]
+    #[test]
+    fn test_bigint03() {
+        use num_bigint_03::ToBigInt;
+
+        let tests = varint_test_cases_from_spec();
+
+        for t in tests.iter() {
+            let value = super::deser_cql_value(&ColumnType::Varint, &mut &*t.encoding).unwrap();
+            assert_eq!(CqlValue::Varint(t.value.to_bigint().unwrap().into()), value);
+        }
+    }
+
+    #[cfg(feature = "num-bigint-04")]
+    #[test]
+    fn test_bigint04() {
+        use num_bigint_04::ToBigInt;
+
+        let tests = varint_test_cases_from_spec();
 
         for t in tests.iter() {
             let value = super::deser_cql_value(&ColumnType::Varint, &mut &*t.encoding).unwrap();
-            assert_eq!(CqlValue::Varint(t.value.clone().into()), value);
+            assert_eq!(CqlValue::Varint(t.value.to_bigint().unwrap().into()), value);
         }
     }
 
diff --git a/scylla-cql/src/frame/value.rs b/scylla-cql/src/frame/value.rs
index 47a0994e4e..7d4dbc0835 100644
--- a/scylla-cql/src/frame/value.rs
+++ b/scylla-cql/src/frame/value.rs
@@ -114,6 +114,20 @@ impl From<CqlVarint> for num_bigint_03::BigInt {
     }
 }
 
+#[cfg(feature = "num-bigint-04")]
+impl From<num_bigint_04::BigInt> for CqlVarint {
+    fn from(value: num_bigint_04::BigInt) -> Self {
+        Self(value.to_signed_bytes_be())
+    }
+}
+
+#[cfg(feature = "num-bigint-04")]
+impl From<CqlVarint> for num_bigint_04::BigInt {
+    fn from(val: CqlVarint) -> Self {
+        num_bigint_04::BigInt::from_signed_bytes_be(&val.0)
+    }
+}
+
 /// Native CQL date representation that allows for a bigger range of dates (-262145-1-1 to 262143-12-31).
 ///
 /// Represented as number of days since -5877641-06-23 i.e. 2^31 days before unix epoch.
@@ -784,6 +798,19 @@ impl Value for num_bigint_03::BigInt {
     }
 }
 
+#[cfg(feature = "num-bigint-04")]
+impl Value for num_bigint_04::BigInt {
+    fn serialize(&self, buf: &mut Vec<u8>) -> Result<(), ValueTooBig> {
+        let serialized = self.to_signed_bytes_be();
+        let serialized_len: i32 = serialized.len().try_into().map_err(|_| ValueTooBig)?;
+
+        buf.put_i32(serialized_len);
+        buf.extend_from_slice(&serialized);
+
+        Ok(())
+    }
+}
+
 impl Value for &str {
     fn serialize(&self, buf: &mut Vec<u8>) -> Result<(), ValueTooBig> {
         let str_bytes: &[u8] = self.as_bytes();
diff --git a/scylla-cql/src/frame/value_tests.rs b/scylla-cql/src/frame/value_tests.rs
index 66d383a2c0..79cda0cfbf 100644
--- a/scylla-cql/src/frame/value_tests.rs
+++ b/scylla-cql/src/frame/value_tests.rs
@@ -97,10 +97,8 @@ fn cql_varint_serialization() {
     }
 }
 
-#[cfg(feature = "num-bigint-03")]
-#[test]
-fn bigint03_serialization() {
-    let cases_from_the_spec: &[(i64, Vec<u8>)] = &[
+fn varint_test_cases_from_spec() -> Vec<(i64, Vec<u8>)> {
+    vec![
         (0, vec![0x00]),
         (1, vec![0x01]),
         (127, vec![0x7F]),
@@ -109,10 +107,18 @@ fn bigint03_serialization() {
         (-1, vec![0xFF]),
         (-128, vec![0x80]),
         (-129, vec![0xFF, 0x7F]),
-    ];
+    ]
+}
+
+#[cfg(any(feature = "num-bigint-03", feature = "num-bigint-04"))]
+fn generic_num_bigint_serialization<B>()
+where
+    B: From<i64> + Value + SerializeCql,
+{
+    let cases_from_the_spec: &[(i64, Vec<u8>)] = &varint_test_cases_from_spec();
 
     for (i, b) in cases_from_the_spec {
-        let x = num_bigint_03::BigInt::from(*i);
+        let x = B::from(*i);
         let b_with_len = (b.len() as i32)
             .to_be_bytes()
             .iter()
@@ -123,19 +129,22 @@ fn bigint03_serialization() {
     }
 }
 
+#[cfg(feature = "num-bigint-03")]
+#[test]
+fn bigint03_serialization() {
+    generic_num_bigint_serialization::<num_bigint_03::BigInt>()
+}
+
+#[cfg(feature = "num-bigint-04")]
+#[test]
+fn bigint04_serialization() {
+    generic_num_bigint_serialization::<num_bigint_04::BigInt>()
+}
+
 #[test]
 fn bigdecimal_serialization() {
     // Bigint cases
-    let cases_from_the_spec: &[(i64, Vec<u8>)] = &[
-        (0, vec![0x00]),
-        (1, vec![0x01]),
-        (127, vec![0x7F]),
-        (128, vec![0x00, 0x80]),
-        (129, vec![0x00, 0x81]),
-        (-1, vec![0xFF]),
-        (-128, vec![0x80]),
-        (-129, vec![0xFF, 0x7F]),
-    ];
+    let cases_from_the_spec: &[(i64, Vec<u8>)] = &varint_test_cases_from_spec();
 
     for exponent in -10_i32..10_i32 {
         for (digits, serialized_digits) in cases_from_the_spec {
diff --git a/scylla-cql/src/types/serialize/value.rs b/scylla-cql/src/types/serialize/value.rs
index 68e7080619..e61ab8be83 100644
--- a/scylla-cql/src/types/serialize/value.rs
+++ b/scylla-cql/src/types/serialize/value.rs
@@ -246,6 +246,16 @@ impl SerializeCql for num_bigint_03::BigInt {
             .map_err(|_| mk_ser_err::<Self>(typ, BuiltinSerializationErrorKind::SizeOverflow))?
     });
 }
+#[cfg(feature = "num-bigint-04")]
+impl SerializeCql for num_bigint_04::BigInt {
+    impl_serialize_via_writer!(|me, typ, writer| {
+        exact_type_check!(typ, Varint);
+        // TODO: See above comment for num-bigint-03.
+        writer
+            .set_value(me.to_signed_bytes_be().as_slice())
+            .map_err(|_| mk_ser_err::<Self>(typ, BuiltinSerializationErrorKind::SizeOverflow))?
+    });
+}
 impl SerializeCql for &str {
     impl_serialize_via_writer!(|me, typ, writer| {
         exact_type_check!(typ, Ascii, Text);
diff --git a/scylla/Cargo.toml b/scylla/Cargo.toml
index 81d33bcac1..2d59482296 100644
--- a/scylla/Cargo.toml
+++ b/scylla/Cargo.toml
@@ -21,7 +21,8 @@ secret = ["scylla-cql/secret"]
 chrono = ["scylla-cql/chrono"]
 time = ["scylla-cql/time"]
 num-bigint-03 = ["scylla-cql/num-bigint-03"]
-full-serialization = ["chrono", "time", "secret", "num-bigint-03"]
+num-bigint-04 = ["scylla-cql/num-bigint-04"]
+full-serialization = ["chrono", "time", "secret", "num-bigint-03", "num-bigint-04"]
 
 [dependencies]
 scylla-macros = { version = "0.3.0", path = "../scylla-macros" }
@@ -58,6 +59,7 @@ socket2 = { version = "0.5.3", features = ["all"] }
 
 [dev-dependencies]
 num-bigint-03 = { package = "num-bigint", version = "0.3" }
+num-bigint-04 = { package = "num-bigint", version = "0.4" }
 scylla-proxy = { version = "0.0.3", path = "../scylla-proxy" }
 ntest = "0.9.0"
 criterion = "0.4" # Note: v0.5 needs at least rust 1.70.0
diff --git a/scylla/src/transport/cql_types_test.rs b/scylla/src/transport/cql_types_test.rs
index c58a48ddcc..36368479f1 100644
--- a/scylla/src/transport/cql_types_test.rs
+++ b/scylla/src/transport/cql_types_test.rs
@@ -103,10 +103,9 @@ where
     }
 }
 
-#[cfg(feature = "num-bigint-03")]
-#[tokio::test]
-async fn test_varint() {
-    let tests = [
+#[cfg(any(feature = "num-bigint-03", feature = "num-bigint-04"))]
+fn varint_test_cases() -> Vec<&'static str> {
+    vec![
         "0",
         "1",
         "127",
@@ -117,11 +116,23 @@ async fn test_varint() {
         "-129",
         "123456789012345678901234567890",
         "-123456789012345678901234567890",
-    ];
+    ]
+}
 
+#[cfg(feature = "num-bigint-03")]
+#[tokio::test]
+async fn test_varint03() {
+    let tests = varint_test_cases();
     run_tests::<num_bigint_03::BigInt>(&tests, "varint").await;
 }
 
+#[cfg(feature = "num-bigint-04")]
+#[tokio::test]
+async fn test_varint04() {
+    let tests = varint_test_cases();
+    run_tests::<num_bigint_04::BigInt>(&tests, "varint").await;
+}
+
 #[tokio::test]
 async fn test_cql_varint() {
     let tests = [