ABSTRACT Existing research has explored the connection between perceived usefulness and growth mindset, but there are still gaps in our understanding of how the perceived usefulness of second language learning apps (PU-L2LA) relates to L2 learner’s language mindset (LM). Our study seeks to investigate the serial mediating role of flow and motivation intensity in the association between PU-L2LA and LM, as well as the network-level interaction between flow and motivation intensity (MI). This is a cross-sectional study conducted with a convenience sample of 524 Chinese university students, aiming to assess PU-L2LA, flow, MI, and LM. The results of the mediation analyses reveal that flow and MI play sequential mediating roles in linking PU-L2LA to LM. Furthermore, through network analysis techniques, two key bridge indicators (“The experience is extremely rewarding.” and “After I graduate from college, I will continue to study English and try to improve.”) were identified as important links between flow and MI. These findings contribute to a deeper understanding of how PU-L2LA influences LM and the underlying mechanisms involved. They highlight the importance of considering flow experiences and MI in promoting a positive language mindset among learners. Educators, app developers, and researchers can utilize these insights to design effective interventions, enhance engagement, and optimize language learning outcomes.