This paper investigates the effects of computer self-efficacy beliefs of pre-service teachers on their achievement in graphic design theory and practical design. The study adopted a quantitative research approach using non-equivalent groups' pre-test-post-test quasi-experimental research design. A sample of 81 participants was purposively drawn from second-year pre-service art teachers in colleges of education in Nigeria. Three research questions and three hypotheses were formulated to guide the study. The research instruments used were computer self-efficacy scale adopted from the literature, teacher-made graphic design achievement tests and a graphic design assessment rubric developed by the researchers. Data collected from the study were analysed using inferential statistics and Analysis of Covariance (ANCOVA). The findings showed that computer self-efficacy beliefs of the pre-service teachers had a positive effect on their achievements as those with high computer self-efficacy beliefs performed better than those with low computer self-efficacy beliefs in all the groups in overall graphic design and practical graphic design achievement. However, their self-efficacy beliefs were found to have no significant effect on their theory achievements. It was concluded that teacher educators should endeavour to help pre-service teachers develop high computer self-efficacy beliefs to enable them to benefit maximally from ICT-integrated curricula.