Understanding how young adolescent learners interact with mobile vocabulary learning applications can aid them in becoming more engaged with the information and feedback they are receiving. Inspired by the literature on learner-oriented feedback practice, this study asked two research questions: 1) what kind of feedback from the mobile apps can predict their learning experience, and 2) what features are useful in the support of self-assessment practice? Both survey data (n = 259) and interview data (n = 12) were collected from students at a junior school in southern China. Quantitative analysis suggests that high levels of satisfaction and perceived usefulness are associated with two factors: 1) visualizing the learning gaps with reference to external standardized tests and curricula, and 2) encouraging independent rather than social learning strategies. The qualitative data identified four main features or principles which may support young adolescent learners’ use of apps for self-assessment practice: 1) explicit links to curricula and tests; 2) immediate feedback on answers and learning strategies with more similar tasks; 3) maintaining relationships with teachers and peers, and 4) emotional support. Implications include the integration of quick automatic feedback to app users, clear alignment of self-assessment tasks with national curriculum and tests, and stronger emotional and cognitive support from both peers and instructors.