To inform future learning opportunities, we performed a scoping review to identify competencies relevant to physical activity (PA) specialists in supporting the PA and mental health of people experiencing mental health concerns. CINAHL, PsycINFO, and SPORTDiscus databases were searched up to June 22, 2022, for research studies and commentaries. Pertinent text was extracted and subject to content analysis using an inductive approach. Sixty-two competencies from 62 publications were organized into four domains: (a) interacting with mental health care services/systems, (b) responding to mental health concerns, (c) employing PA counseling/coaching to promote mental health among people with diverse mental health needs, and (d) building relationships that are responsive to diverse mental health needs. These findings may serve as a road map for stakeholders interested in developing PA specialists’ confidence to meet the challenges of navigating mental health contexts. Despite consistency across sources, points of divergence warrant consideration from learning institutions and professional bodies.