Introduction: Knowing who we are and what we are living for helps us to better adjust in everyday life and confront negative life events, especially for adolescents who are going through critical developmental periods when changes in life could bring both psychopathology risk yet opportunity to achieve a better self. The current study focused on mental time travel, the mental visit to the past or future, and examined the impact on adolescents' perceived meaning in life, with the potential mediating factor of self-continuity. Methods: A total of 1543 high school students aged 12 to 18 years old (M[subscript age] = 15.02, SD[subscript age] = 1.58, 52% girls) from Jiangsu Province, China were recruited in a two-wave longitudinal survey that separated by an interval of 6 months. Participants reported their proneness to engage in nostalgia or future prospection at T1 and sense of self-continuity at T2, while the perceived meaning in life were reported at both time points. The latent structural equation models were established with items as indicators for all study variables. Results: Mental time travel, including both nostalgia and future prospection, facilitated adolescent meaning in life via increased self-continuity, except that future prospection showed only positive indirect effect, while nostalgia demonstrated direct yet negative impact on meaning in life after accounting for the positive mediation effect. Conclusions: Findings highlighted the distinct effects of the past- and future-oriented mental time travel on adolescent meaning in life, and provided insights for promoting adolescent psychological adjustment.