The development of secondary mitral regurgitation (MR) due to left ventricular dysfunction, also known as functional MR, is strongly associated with a poor prognosis in patients with heart failure. The mechanisms underlying secondary MR are multifactorial; accurate imaging assessment of secondary MR may be challenging and nuanced; and the appropriate roles of medical, surgical, and interventional therapies for management of secondary MR are controversial and evolving. In this review, the pathophysiology, evaluation, and prognosis of secondary MR in patients with heart failure are discussed, and we evaluate in detail the evidence for the various therapeutic approaches for secondary MR, including guideline-directed medication for left ventricular dysfunction, cardiac resynchronization therapy and revascularization when appropriate, and mitral valve surgery and transcatheter interventions. The role of a multidisciplinary heart team in determining the optimal management strategy for secondary MR is also discussed.