Sustainable professional development of the young generation is a foundation for the present, a resource for the future, and it makes a significant contribution to the economic, environmental, and social stability of our society. As never before, professional self-identity and realistic professional plans become relevant for the persistent career development of modern schoolchildren and students. The present article theoretically substantiated three factors that are fundamental for studying the psychological characteristics of the high school students’ professional plans: personality traits, conscious self-regulation, and career adaptability. The empirical study had its purpose to examine carefully the relationship between personality traits, conscious self-regulation, career adaptability, and professional plans of high school students in the Russian schools. To this end, a conceptual model of intrapersonal and regulatory predictors of the certainty and sustainability of the young people's professional plans was proposed and tested on a sample of schoolchildren in grades 9, 10, and 11 (N = 675). Methods: “Self-Regulation Profile Questionnaire, SRPQM-2020” by V.I. Morosanova, the Russian adaptation of “Career Adapt-Abilities Scale, CAAS” by M. Savikas and E. Porfeli, the Russian adaptation of the “The Big Five Inventory-2 (BFI-2)” by K. Soto and O. John, as well as the ad hoc questionnaire on the students' professional plans. The structural modeling analysis of the obtained data demonstrated that certainty and stability of the professional plans in the high school students depend on the developmental level of their career adaptability, including all career-oriented resources: concern, control, curiosity, confidence. At the same time, the conscious self-regulation of achieving goals also contributes to the certainty and sustainability of students' professional / academic plans through their career adaptability, which acts as a mediator of this influence. As for personality traits, they make an indirect contribution to the professional plans of young people, determining the development of conscious self-regulation and career adaptability. The results obtained reveal the importance of general psychological (conscious self-regulation) and professionally oriented (career adaptability) resources of students in their professional development.