To gain more insight into the optimal strategy to achieve weight loss and weight loss maintenance in overweight and obese cancer survivors after completion of initial treatment, this systematic review aimed to provide an overview of the literature on intervention effects on weight, to describe intervention components used in effective interventions, to identify and synthesize behaviour change techniques (BCTs) and to assess the frequency with which these BCTs were used in effective interventions. Six databases were searched for original research articles describing weight changes in adult overweight cancer survivors after participation in a lifestyle intervention initiated after completion of initial treatment. Two researchers independently screened the retrieved papers and extracted BCTs using the BCT Taxonomy version 1. Thirty-two papers describing 27 interventions were included. Interventions that were evaluated with a robust study design (n=8) generally showed <5% weight loss and did not evaluate effects at ≥12months after intervention completion. Effective interventions promoted both diet and physical activity and used the BCTs goal setting (behaviour), action planning, social support (unspecified) and instruction on how to perform the behaviour. The results of this first review on intervention components of effective interventions could be used to inform intervention development and showed a need for future publications to report long-term effects, a detailed intervention description and an extensive process evaluation. This study contributed to increasing knowledge on the optimal strategy to achieve weight loss, which is recommended for overweight cancer survivors to improve health outcomes.