Background: Health outcome trials have provided strong evidence that participating in regular physical activity can improve the quality of life and health of post-treatment breast cancer survivors. Focus is now needed on how to promote changes in physical activity behaviour among this group. Purpose: This systematic review examines the efficacy of behavioral interventions for promoting physical activity among post-treatment breast cancer survivors. Methods: Behavioural intervention studies published up until July 2012 were identified through a systematic search of two databases: MEDLINE and CINAHL; and by searching reference lists of relevant publications and scanning citation libraries of project staff. Results: Eight out of the ten identified studies reported positive intervention effects on aerobic physical activity behaviour, ranging from during the intervention period to 6 months post-intervention. Only two studies reported intervention effect-sizes. The identification of factors related to efficacy was not possible due to the limited number and heterogeneity of studies included, as well as the lack of effect sizes reported. Nonetheless, an examination of the eight studies that did yield significant intervention effects suggests that 12-week interventions employing behavior change techniques (e.g., self-monitoring, goal-setting) derived from a variety of theories and delivered in a variety of settings (i.e., one-on-one, group, home) can be effective at changing the aerobic physical activity behavior of breast cancer survivors in the mid-to long-term. Conclusion: Behavioral interventions do hold promise for effectively changing physical activity behavior among breast cancer survivors. However, future research is needed to address the lack of studies exploring long-term intervention effects, mediators of intervention effects and interventions promoting resistance-training activity, and to address issues impacting on validity, such as the limited use of objective physical activity measures and the use of convenience samples. Implications for cancer survivors: Identifying effective ways of assisting breast cancer survivors to adopt and maintain physical activity is important for enhancing the well-being and health outcomes of this group.