On April 4, 2019, the FDA approved a supplemental new drug application for palbociclib (IBRANCE), to expand the approved indications in women with hormone receptor (HR)-positive, HER2-negative advanced or metastatic breast cancer (MBC) in combination with an aromatase inhibitor or fulvestrant, to include men. Palbociclib was first approved in 2015 for use in combination with letrozole for the treatment of estrogen receptor-positive, HER2-negative advanced breast cancer as initial endocrine-based therapy in postmenopausal women and subsequently in 2016 in combination with fulvestrant in women with HR-positive, HER2-negative advanced breast cancer with disease progression following endocrine therapy. The current approval was primarily based on the results of the PALOMA-2 and PALOMA-3 trials and, supported by real-world data from electronic health records and insurance claims. To support the safety evaluation in male patients, data from two phase I studies with palbociclib and safety information from the global safety database, were also reviewed. This article summarizes FDA decision-making and data supporting the approval of palbociclib for the treatment of male patients with HR-positive, HER2-negative advanced or MBC.