The aim of this study was to determine whether perception of risk and accessibility of cannabis predicted the age of initiation of cannabis use among Jamaican secondary school students. Data from a nationally representative sample were analysed. Descriptive statistical analysis was done while binary logistic regression was used to compute point estimates and confidence intervals (CIs). The median age of initiation was 13 years. Gender was a predictor of age of initiation, with females having 39% less risk of initiating cannabis use at the age of 13 years or younger before adjusting for covariates (crude odds ratio [COR]: 0.61; 95% CI: 0.48, 0.77), which increased to 42% reduced risk of initiating cannabis use at the age of 13 years or younger after adjusting for covariates (adjusted OR [AOR]: 0.58; 95% CI: 0.39, 0.85). There was a significant inverse association between grade level in school and age of initiation of cannabis use, with 11th grade students having a significantly reduced risk of commencing cannabis use at the age of 13 years or younger (COR: 0.41; 95% CI: 0.23, 0.70; AOR: 0.41; 95% CI: 0.23, 0.72). Participants who perceived cannabis use as moderately harmful were 67% less likely to initiate cannabis use at the age of 13 years or younger compared to participants who thought it was not harmful (AOR: 0.33; 95% CI: 0.12, 0.88). Perceptions of access to cannabis did not predict age of initiation of cannabis use. Being female, being in the 11th grade and the perception that cannabis use was moderately harmful significantly reduced the risk of initiating cannabis use at the age of 13 years or younger.