Background <p>While physical activity behaviours have been explored during the COVID-19 pandemic, little is known about the social contexts in which physical activity took place during this time of crisis. The purpose of this longitudinal study was to explore the physical activity-related social contexts in which young people (aged 15–24) engaged during the first two years of the COVID-19 pandemic in Ontario, Canada. Specific objectives included identifying: (1) how patterns of engagement in social contexts changed over time; and (2) demographic/descriptive predictors of social context-related class membership.</p> Methods <p>Online surveys were completed from: (1) July–September 2020; (2) November 2020–January 2021; and (3) July 2021–January 2022. Data on gender, living situation, physical activity, and physical activity-related social contexts were collected. Latent transition analysis was conducted to determine how participant’s social contexts changed over time and chi-squared tests were used to assess predictors of latent profile membership.</p> Results <p>Participants (<i>n</i> = 328; <i>M</i>_age = 22.95) were categorized into three latent classes: 1 = mainly active alone; 2 = limited physical activity in all contexts; and 3 = mainly active with others. At Time 1, nearly 70.0% of participants were in Class 1; at Times 2 and 3, most participants (62.1% and 53.6%, respectively) were in Class 2. From Times 1–2, most participants (67.1%) transitioned from Class 1 to Class 2. From Times 2–3, more than 75.0% of participants remained in their respective classes. Class membership was associated with various predictors at different time points.</p> Conclusion <p>Results underscore the need to promote participation in a variety of physical activity-related social contexts, particularly during times of crisis.</p>