Hydroformylation of olefins with H₂ and CO is an important industrial process for aldehyde production, and developing Earth-abundant catalysts with high catalytic activity and stability remains challenging. Here, we synthesize a rhodium-like high-efficiency single-atom cobalt catalyst over β-Mo₂C toward olefin hydroformylation. During the hydroformylation of propene, the single atomic cobalt catalyst achieves a turnover number of 3,834 and a turnover frequency of 749 h⁻¹, which to our knowledge surpasses all the reported heterogeneous cobalt-based catalysts and approaches the performance of rhodium catalysts. Moreover, the catalyst can be reused five times without an obvious activity decline, confirming the excellent stability of single-atom Co supported on β-Mo₂C. We demonstrate that a Co₁-Mo_xC_y motif forms on the carbide surface with electronic metal-support interaction (EMSI). Such an EMSI effect plays a pivotal role in optimizing the charge density, reducing the reaction barrier, and stabilizing the active site.