<p>Previous literature indicates that internet use, depression, and life satisfaction are intertwined in a digital age. Yet, the nature of the relationships between these three variables is still debated, and robust longitudinal evidence from non-Western contexts remains scarce. Addressing this gap, the current study investigates whether depression mediates the internet use-life satisfaction link longitudinally in China. Using a nationally representative, three-wave panel sample of 4,796 Chinese adults, the longitudinal mediation analysis revealed that internet use positively predicted subsequent changes in depression and negatively predicted life satisfaction. Depression, in turn, negatively predicted life satisfaction and exhibited a significant longitudinal mediation effect. These findings establish depression as a critical mechanism underlying the internet’s impact on life satisfaction in the Chinese context and contribute to a more nuanced understanding of digital media effects in non-Western societies.</p>