Nivolumab, a programmed cell death-1 inhibitor, has demonstrated prolonged survival benefit in patients with advanced melanoma. Bempegaldesleukin (BEMPEG; NKTR-214), a first-in-class CD122-preferential IL-2 pathway agonist, provides sustained signaling through the IL-2βγ receptor, which activates effector T and natural killer cells. In the Phase I/II PIVOT-02 trial, the combination of bempegaldesleukin plus nivolumab was well-tolerated and demonstrated clinical activity as first-line therapy in metastatic melanoma. Here, we describe the design of and rationale for the Phase III, global, randomized, open-label PIVOT IO 001 trial comparing bempegaldesleukin plus nivolumab with nivolumab alone in patients with previously untreated, unresectable or metastatic melanoma. Primary end points include objective response rate, progression-free survival and overall survival. Key secondary end points include further investigation of safety/tolerability, previously assessed in the PIVOT-02 trial. Clinical Trial Registration: NCT03635983 (ClinicalTrials.gov).