H₂ in a CO₂ atmosphere may serve as a potential solution to the early Mars climate paradox, but its unknown sources cast doubts on the proposed mechanism. Impact cratering is an energetic process that may modify the surface redox budget. Here, we investigate the potential influence of impact-related melt oxidation and serpentinization on global climate conditions. We show that impact melt and the projectile's significant oxidizing potential during basin-forming impacts (Basin size ≥1,250 km) result in sufficient H₂ to raise the global mean temperature to above 273K, which lasts for up to 10⁵ − 10⁶ yr considering rate-limited regime. Impact-induced serpentinization has limited consequences on the global climate in comparison. Episodic warming after large impacts may have enabled the presence of liquid water for up to several million years in the Noachian, resulting in the chemical evolution of the planet's surface co-evolving with the planetary atmosphere in an episodic manner.