Identity and academic motivation are particularly at stake before the major transition to higher education. However, few studies have explored their changes and their longitudinal bidirectional links. To fill this gap, a three-wave study from the end of the 11th grade to the end of the 12th grade was conducted to explore changes in identity processes and academic motivation and to investigate how they might be interconnected over time. 599 adolescents (mean age 17.4; 59% girls) completed questionnaires containing measures about identity processes and three types of academic motivation: autonomous, controlled, and impersonal. Throughout the study span of one year, four identity processes increased: commitment making, identification with commitment, exploration in breadth and exploration in depth, while the process of ruminative exploration decreased. Simultaneously, late adolescents encountered an increase in impersonal motivation, more salient for boys. The results also revealed unidirectional links from motivation to identity processes, with no gender or age moderator effects: exploration in breadth and exploration in depth were positively predicted by autonomous motivation, ruminative exploration was positively predicted by autonomous, controlled, and impersonal motivation. In addition, impersonal motivation negatively predicted commitment making. On the other hand, identification with commitment positively predicted autonomous motivation. Practical implications are discussed.