Background We examined the cardiovascular risk of abatacept compared with tumor necrosis factor ( TNF ) inhibitors in patients with rheumatoid arthritis with and without diabetes mellitus ( DM ). Methods and Results We conducted a cohort study of patients with rheumatoid arthritis who newly started abatacept or TNF inhibitors using claims data from Medicare and MarketScan. The primary outcome was a composite cardiovascular end point of myocardial infarction ( MI ), stroke/transient ischemic attack, and coronary revascularization. To account for >60 baseline characteristics, abatacept initiators were 1:1 propensity score ( PS ) matched to TNF initiators in each database. Cox proportional hazards models estimated hazard ratio ( HR ) and 95% confidence interval ( CI ) in the PS ‐matched cohort per database. A fixed‐effects meta‐analysis pooled database‐specific HR s. We included a total of 13 039 PS ‐matched pairs of abatacept and TNF inhibitor initiators (6103 pairs in Medicare and 6936 pairs in MarketScan). A total of 34.7% in Medicare and 19.8% in MarketScan had baseline DM . The HR (95% CI ) for the primary outcome associated with abatacept use versus TNF inhibitor was 0.81 (0.66–0.99) in Medicare and 0.95 (0.74–1.23) in MarketScan, with a pooled HR of 0.86 (95% CI, 0.73–1.01; P =0.3 for heterogeneity). The risk of the primary outcome was lower in abatacept initiators versus TNF inhibitors in the DM subgroup, with a pooled HR of 0.74 (95% CI, 0.57–0.96; P =0.7 for heterogeneity), but not in the non‐ DM subgroup, with a pooled HR of 0.94 (95% CI, 0.77–1.14; P =0.4 for heterogeneity). Conclusions In this large population‐based cohort of patients with rheumatoid arthritis, abatacept use appeared to be associated with a modestly reduced cardiovascular risk when compared with TNF inhibitor use, particularly in patients with DM.