Digital approaches to loneliness are increasingly scalable, but recent syntheses show heterogeneous and sometimes null effects, with limited evidence from African adults. I evaluated an eight-week Digital Physical Activity Intervention (DPAI) that integrated guided home-based activity, synchronous peer interaction, self-monitoring, microlessons and motivational support. In a closed-cohort stepped-wedge cluster-randomised trial, 71 Nigerian adults in 18 clusters were observed across five common periods and crossed from control to DPAI according to four randomised rollout sequences.