Temporary transvenous cardiac pacing (TVP) is a critical intervention that emergency physicians perform infrequently in clinical practice. Prior simulation studies revealed that emergency medicine (EM) residents and board-certified emergency physicians perform TVP poorly during checklist-based assessments. Our objective in this report was to describe the design and implementation of a simulation-based mastery learning (SBML) curriculum and evaluate its impact on EM residents' ability to perform TVP. An expert panel of emergency physicians and cardiologists set a minimum passing standard (MPS) for a previously developed 30-item TVP checklist using the Mastery Angoff approach. Emergency medicine residents were assessed using this checklist and a high-fidelity TVP task trainer. Residents who did not meet the MPS during baseline testing viewed a procedure video and completed a 30-minute individual deliberate practice session before retesting. Residents who did not meet the MPS during initial post-testing completed additional deliberate practice and assessment until meeting or exceeding the MPS. The expert panel set an MPS of correctly performing 28 (93.3%) checklist items. Fifty-seven EM residents participated. Mean checklist scores improved from 13.4 (95% CI 11.8-15.0) during baseline testing to 27.5 (95% CI 26.9-28.1) during initial post-testing (P < 0.01). No residents met the MPS at baseline testing. The 21 (36.8%) residents who did not meet the MPS during initial post-testing all met or exceeded the MPS after completing one additional 30-minute deliberate practice session. Emergency medicine residents demonstrated significantly improved TVP performance with reduced variability in checklist scores after completing a simulation-based mastery learning curriculum.