Social norms are unwritten rules about how to behave in a particular group or culture, and have been shown to impact behaviour change in many domains (Draper et al., 2015). However, there are equivocal findings regarding the influence of social norms in the context of physical activity (PA), which may be attributed to inconsistencies in the definition and measurement of social norms (Ball et al., 2010). The present scoping review analyzed the literature examining relationships between social norms and PA to specifically investigate how researchers have defined and measured social norms and how social norm-based interventions have been conducted. Articles were retrieved based on keyword searches of five electronic databases and manual searches of 14 relevant journals. A total of 129 articles meeting the inclusion criteria were reviewed. The majority of articles (n = 119) measured subjective norms within the theory of planned behaviour (TPB) and revealed inconclusive results regarding the ability of subjective norms to predict PA intentions and behaviours. The TPB specific results also illustrated several factors that should be considered when examining the role of subjective norms in the context of PA behaviours, which included measurement issues, potential covariates of subjective norms, and moderators of the subjective norm-intention relationship. Among studies not grounded within the TPB (n = 10), three studies measured, and seven manipulated, other forms of social norms (e.g., descriptive norms) and found promising results in facilitating PA. Researchers may use the current findings to target appropriate populations for interventions, refine measurement, and incorporate relevant types of norms.