By adopting a longitudinal multiple‐case study approach, we tracked two Swahili language learners’ motivational trajectories over 20 months from 2020 to 2022 via investment as a sociological lens. Data were collected through four semi‐structured interviews with each participant. Thematic analysis of the data revealed that the two focal learners chose to invest in learning Swahili upon matriculation due to the influence of family capital and ideology, imagined professional identity, and perceived cultural capital concomitant with their learning. Moreover, their sustained learning endeavors can largely be attributed to academic support from teachers, positive self‐positioning as legitimate Swahili speakers in multi‐dimensional spaces, and their efforts to eliminate stereotypes. We argue that their Swahili learning motivation underwent a spiral‐rise development, and through sustained efforts to learn the Swahili language, learners appear to be able to translate capital into new forms and construct imagined identities. This article concludes by discussing pedagogical implications for the development of multilingual education in China.