Grit, defined as passion and perseverance to achieve long‐term goals, has been associated with adolescents' optimal academic and psychological functioning. However, the role of grit in adolescents' positive youth development (PYD)—characterized by the 5Cs known as competence, confidence, connection, character, and caring—remains unknown. Using latent cross‐lagged panel modeling, this study examined the longitudinal relations between the triarchic model of grit (TMG) dimensions (i.e., perseverance of effort, consistency of interest, and adaptability to situations), and the 5Cs of PYD while controlling for specific socio‐demographic covariates (gender, age, SES, and school type). Data were obtained from 1620 Filipino adolescents (Mage = 17.15; SDage = 1.00) in November 2021 and May 2022. Results show that grit dimensions predicted subsequent PYD dimensions, but not vice versa. Specifically, while perseverance and adaptability were linked to higher levels of competence, confidence, and character, consistency was associated with lower levels of competence and confidence six months later. Results highlight the importance of grit's dimensions in facilitating PYD characteristics among adolescents, especially efficacy‐related Cs (competence and confidence). Theoretical and practical implications in promoting adolescent thriving and well‐being are discussed.