BackgroundCompleting high school enables access to educational and employment opportunities associated with better physical and mental health and improved quality of life. Identifying modifiable factors that promote optimal educational trajectories for youth experiencing disadvantage is an important research focus. Social inclusion has been theorised to play a role in promoting better educational outcomes for this priority population, however limited research has examined this relationship.MethodThis study used three waves of data from the state‐representative Australian arm of the International Youth Development Study (IYDS) (youngest cohort, N = 733; 54% female, 95% Australian born) to examine the extent to which vulnerability in primary school (Grade 5; Mage = 10.97, SD = 0.38) and social inclusion in mid‐adolescence (Year 10; Mage = 15.50, SD = 0.53), were associated with school completion in young adulthood (post‐secondary; Mage = 19.02, SD = 0.43).ResultsRegression models identified an interaction between social inclusion and vulnerability (OR = 1.37, 95% CI [1.06, 1.77], p = .016), indicating that the association between vulnerability and school completion varied as a student's level of social inclusion increased. Higher social inclusion was beneficial for youth with lower levels of vulnerability but did not appear to influence school completion for the most vulnerable students.ConclusionsFor many young people, promoting social inclusion may support engagement in education and play a protective role. However, further research is needed to better understand the role of social inclusion for highly vulnerable youth, particularly the mechanisms via which social inclusion may have differential effects on school completion.