<p>Life satisfaction has received increasing attention in psychological research, but there remain mixed results about the developmental trajectories of students’ life satisfaction, and little is known about the potential reciprocal relations between parental autonomy support and life satisfaction. Using information from nationally representative elementary school students (Grade 4–6, <i>N</i> = 2607, <i>k</i> = 171 schools) and secondary school students (Grade 7–9, <i>N</i> = 2590, <i>k</i> = 162 schools) in South Korea, the current study examined the developmental trajectories of students’ life satisfaction and the relations between life satisfaction and parental autonomy support. Latent neighbor change models showed that life satisfaction decreased for both elementary and secondary school students. Latent cross-lagged panel models showed that parental autonomy support and life satisfaction were reciprocally linked over time among secondary school students. Parental autonomy support predicted subsequent life satisfaction, and life satisfaction positively predicted parental autonomy support. However, the effects of parental autonomy support on subsequent life satisfaction were not significant for elementary school students. Parental autonomy support tended to increase in importance from elementary to secondary school. Moreover, sensitivity analyses indicated gender differences in the development of life satisfaction. These findings contribute to ongoing research to develop more tailored programs to support the life satisfaction of struggling students.</p>