BACKGROUND: In people living with polycystic kidney disease (PKD), physical inactivity may contribute to poor health-related quality of life (HRQoL). To date, no research has elucidated the impact of a PKD-specific physical activity programme on HRQoL and physical health. This substudy of the Kidney BEAM Trial evaluated the impact of a PKD-specific 12-week educational and physical activity digital health intervention for people living with PKD. METHODS: This study was a mixed-methods, single-blind, randomized waitlist-controlled trial. Sixty adults with a diagnosis of PKD were randomized 1:1 to the intervention or a waitlist control group. Primary outcome was difference in the Kidney Disease QoL Short Form 1.3 Mental Component Summary (KDQoL-SF1.3 MCS) between baseline and 12 weeks. Six participants completed individualized semi-structured interviews. RESULTS: All 60 individuals (mean 53 years, 37% male) were included in the intention-to-treat analysis. At 12 weeks, there was a significant difference in mean adjusted change in KDQoL MCS score between the intervention group and waitlist control [4.2 (95% confidence interval 1.0-7.4) arbitrary units, CONCLUSION: A PKD-specific digital health educational and physical activity intervention is acceptable and has the potential to improve HRQoL. Further research is needed to better understand how specific education and lifestyle management may help to support self-management behaviour.