diff --git a/python/requirements/rllib/requirements_rllib.txt b/python/requirements/rllib/requirements_rllib.txt
index a22521308a29..89a0b0555848 100644
--- a/python/requirements/rllib/requirements_rllib.txt
+++ b/python/requirements/rllib/requirements_rllib.txt
@@ -22,7 +22,7 @@ kaggle_environments==1.7.11
 mlagents==0.26.0
 mlagents_envs==0.26.0
 # For tests on PettingZoo's multi-agent envs.
-pettingzoo==1.8.2
+pettingzoo==1.20.1
 # For testing in MuJoCo-like envs (in PyBullet).
 pybullet==3.1.7
 # For tests on RecSim and Kaggle envs.