diff --git a/core/application/src/query_runner.rs b/core/application/src/query_runner.rs
index 0c809a9d6..72aee97d0 100644
--- a/core/application/src/query_runner.rs
+++ b/core/application/src/query_runner.rs
@@ -162,8 +162,13 @@ impl SyncQueryRunnerInterface for QueryRunner {
         todo!()
     }
 
-    fn is_valid_node(&self, _id: &NodePublicKey) -> bool {
-        todo!()
+    fn is_valid_node(&self, id: &NodePublicKey) -> bool {
+        // TODO(matthias): we can use `is_some_and` once we update the rust version to 1.70
+        if let Some(node_info) = self.get_node_info(id) {
+            node_info.stake.staked >= self.get_staking_amount().into()
+        } else {
+            false
+        }
     }
 
     fn get_staking_amount(&self) -> u128 {
diff --git a/core/application/src/tests.rs b/core/application/src/tests.rs
index 0ebd1f112..2289ad43c 100644
--- a/core/application/src/tests.rs
+++ b/core/application/src/tests.rs
@@ -1023,3 +1023,58 @@ async fn test_validate_txn() {
     );
     assert_eq!(res.txn_receipts[0], query_runner.validate_txn(req));
 }
+
+#[test]
+async fn test_is_valid_node() {
+    let (update_socket, query_runner) = init_app(None).await;
+
+    let owner_secret_key = AccountOwnerSecretKey::generate();
+    let node_secret_key = NodeSecretKey::generate();
+
+    // Stake minimum required amount.
+    let minimum_stake_amount = query_runner.get_staking_amount();
+    deposit(
+        minimum_stake_amount.into(),
+        Tokens::FLK,
+        owner_secret_key,
+        &update_socket,
+        1,
+    )
+    .await;
+    stake(
+        minimum_stake_amount.into(),
+        node_secret_key.to_pk(),
+        owner_secret_key,
+        &update_socket,
+        2,
+    )
+    .await;
+    // Make sure that this node is a valid node.
+    assert!(query_runner.is_valid_node(&node_secret_key.to_pk()));
+
+    // Generate new keys for a different node.
+    let owner_secret_key = AccountOwnerSecretKey::generate();
+    let node_secret_key = NodeSecretKey::generate();
+
+    // Stake less than the minimum required amount.
+    let minimum_stake_amount = query_runner.get_staking_amount();
+    let less_than_minimum_skate_amount = minimum_stake_amount / 2;
+    deposit(
+        less_than_minimum_skate_amount.into(),
+        Tokens::FLK,
+        owner_secret_key,
+        &update_socket,
+        1,
+    )
+    .await;
+    stake(
+        less_than_minimum_skate_amount.into(),
+        node_secret_key.to_pk(),
+        owner_secret_key,
+        &update_socket,
+        2,
+    )
+    .await;
+    // Make sure that this node is not a valid node.
+    assert!(!query_runner.is_valid_node(&node_secret_key.to_pk()));
+}