Objectives: The aim of this study was to describe baseline characteristics, and periprocedural and mid-term outcomes of patients undergoing transcatheter mitral valve interventions post-transcatheter aortic valve replacement (TAVR) and examine their clinical benefit. Background: The optimal management of residual mitral regurgitation (MR) post-TAVR is challenging. Methods: This was an international registry of 23 TAVR centers. Results: In total, 106 of 24,178 patients (0.43%) underwent mitral interventions post-TAVR (100 staged, 6 concomitant), most commonly percutaneous edge-to-edge mitral valve repair (PMVR). The median interval post-TAVR was 164 days. Mean age was 79.5 ± 7.2 years, MR was >moderate in 97.2%, technical success was 99.1%, and 30-day device success rate was 88.7%. There were 18 periprocedural complications (16.9%) including 4 deaths. During a median follow-up of 464 days, the cumulative risk for 3-year mortality was 29.0%. MR grade and New York Heart Association (NYHA) functional class improved dramatically; at 1 year, MR was moderate or less in 90.9% of patients (mild or less in 69.1%), and 85.9% of patients were in NYHA functional class I/II. Staged PMVR was associated with lower mortality versus medical treatment (57.5% vs. 30.8%) in a propensity-matched cohort (n = 156), but this was not statistically significant (hazard ratio: 1.75; p = 0.05). Conclusions: For patients who continue to have significant MR, remain symptomatic post-TAVR, and are anatomically suitable for transcatheter interventions, these interventions are feasible, safe, and associated with significant improvement in MR grade and NYHA functional class. These results apply mainly to PMVR. A staged PMVR strategy was associated with markedly lower mortality, but this was not statistically significant. (Transcatheter Treatment for Combined Aortic and Mitral Valve Disease. The Aortic+Mitral TRAnsCatheter Valve Registry [AMTRAC]; NCT04031274)