The study aimed to estimate the prevalence and correlates of oral hygiene (OH) and hand hygiene (HH) behaviour among school adolescents in three Caribbean countries. In all, 7,476 school adolescents (median age 14 years), from Dominican Republic, Suriname and Trinidad and Tobago responded the cross-sectional “Global School-based Student Health Survey” (GSHS) in 2016-2017. The prevalence poor OH (tooth brushing <2 times/day) was 16.9%, poor HH (not always before meals) was 68.2%, poor HH (not always after toilet) was 28.4% and poor HH (not always with soap) was 52.7%. In adjusted logistic regression analysis, current cannabis use, inadequate fruit and vegetable intake, poor mental health and low parental support increased the odds for poor OH. Rarely or sometimes experiencing hunger, trouble from alcohol use, inadequate fruit and vegetable intake, poor mental health, and low parental support were associated with poor HH (before meals, and/or after toilet, and/or with soap). The survey showed poor OH and HH behaviour practices. Several sociodemographic factors, health risk behaviours, poor mental health and low parental support were found associated with poor OH and/or HH behaviour that can assist with tailoring OH and HH health promotion.