The article presents a study of the relationship of professional identity and subjective well-being of senior students. The sample included 151 students of final courses (3, 4, 5 courses) of St. Petersburg universities in various directions. Measured: professional identity and features of professional choice (questionnaire, author's questionnaire of V.R. Manukyan, MIPI questionnaire of L.B. Schneider, color test of relations), subjective well-being (questionnaire DS-8 of L.V. Kulikov, the happiness scale of M. Fordis). The results showed that students with an effectively developing professional identity are characterized by a high level of activity, a rather high level of happiness with a low level of vigor, tone, relaxedness, calmness, stability, satisfaction, self-criticism. In students with an unformed professional identity, on the contrary, there is a decrease in levels of activity and happiness, combined with higher rates of emotional states. The results suggest that the eudemonic and hedonistic aspects of well-being are in contradictory relations: students' happiness level increases with increased activity in relation to life situations, readiness to overcome obstacles (eudemonic aspect), but with a decrease in the comfort of emotional states (hedonistic aspect). At the same time, eudemonic well-being is largely associated with a formed professional identity, and hedonic well-being with an unformed one.