With the popularity of mobile devices, people are increasingly trying to learn a second language (L2) using mobile applications (apps). The current study examined language learners' perceptions of the usefulness and ease of use of mobile learning apps in relation to language learning flow and satisfaction. University students who were learning Chinese as second language (CSL; n = 183) or learning English as second language (ESL; n = 481) completed scales assessing their perceptions of the apps' usefulness (PU) and ease of use (PEOU), L2 learning flow, and L2 learning satisfaction. Latent profile analysis was used to identify latent groups within CSL learners and within ESL learners, according to their mobile apps perceived usefulness, and perceived ease of use scores. The results showed that: (1) a 3-class solution consisting of a low (least positive) perception group, a medium perception group, and a high perception group was supported in both samples of language learners; (2) in the ESL sample, positive perceptions appeared to have a linear relationship with learning flow and satisfaction; in the CSL sample, this linear relationship was seen for satisfaction but not learning flow. The results of regression analysis validated the moderating role type of language learning plays in the link between PU/PEOU and learning flow and satisfaction with stronger links in ESL learners as compared to CSL learners. Suggestions for further research on app-based L2 learning are discussed.