PURPOSE: This study evaluated the effectiveness of a self-managed home-based moderate intensity walking intervention on psychosocial health outcomes among breast cancer patients undergoing chemotherapy. METHODS: The randomised controlled trial compared a self-managed, home-based walking intervention to usual care alone among breast cancer patients receiving chemotherapy. Outcome measures included changes in self-report measures of anxiety, depression, fatigue, self-esteem, mood and physical activity. Fifty participants were randomised to either the intervention group (n = 25), who received 12 weeks of moderate intensity walking, or the control group (n = 25) mid-way through chemotherapy. Participants in the intervention group were provided with a pedometer and were asked to set goals and keep weekly diaries outlining the duration, intensity and exertion of their walking. Levels of psychosocial functioning and physical activity were assessed pre- and post-intervention in both groups. RESULTS: The intervention had positive effects on fatigue (F = 5.77, p = 0.02), self-esteem (F = 8.93, p ≤ 0.001), mood (F = 4.73, p = 0.03) and levels of physical activity (x (2) = 17.15, p = 0.0011) but not anxiety (F = 0.90, p = 0.35) and depression (F = 0.26, p = 0.60) as assessed using the HADS. We found an 80% adherence rate to completing the 12-week intervention and recording weekly logs. CONCLUSION: This self-managed, home-based intervention was beneficial for improving psychosocial well-being and levels of physical activity among breast cancer patients treated with chemotherapy. TRIAL REGISTRATION: Current Controlled Trials ISRCTN50709297.