Intention is theorised as the proximal determinant of behaviour in many leading theories and yet intention-behaviour discord is prevalent. The purpose of this review was to retrieve, theme and appraise the variables that have been evaluated as the potential moderators of the intention-behaviour relationship in the physical activity (PA) domain. Eligible studies were selected from English peer-reviewed journals and had to report an empirical test of moderation of intention-PA (I-PA) with a third variable. Fifty-seven studies passed the inclusion criteria and these represented 38 different potential moderators of I-PA. Intention stability proved to be the most consistent moderator of I-PA, suggesting that much of the discordance may be from motivational flux between initial intention and eventual behaviour. Anticipated regret and conscientiousness also had evidence as the moderators of I-PA. Perceived control/self-efficacy, planning, extraversion, habit and environmental proximity to recreation showed some evidence for moderation, while gender, agreeableness, openness, body mass index and ethnicity did not appear to moderate I-PA. The findings demonstrate that traditional intention theories may need augmentation to better account for the evidence present in I-PA discordance.