Learner autonomy, which places the great emphasis on the learners' independent roles and responsibilities in their learning process, has become the main concern of language education for over three past decades. It is important to investigate the language learners' self-perception of their autonomous responsibilities, their possession of autonomous abilities, and their enactment of autonomous in-class and out-of-class behaviors. Thereby, the current study adopted features of a mixed-methods research design to examine these autonomous dimensions as perceived by university learners. A sample of eighty English-majored sophomores from Hung Vuong University, Vietnam was recruited for the current study. Their self-perception of autonomous language learning was elicited through two instruments of a thirty-two-item questionnaire and a nine-question semi-structured interview. Then the questionnaire data were quantitatively analyzed and the interview data were qualitatively analyzed. The results of this study indicated that the majority of the participants positively acknowledged the importance of learner autonomy, discerned their gained autonomous learning responsibilities, recognized their existing autonomous abilities, and unveiled some enacted autonomous learning behaviors inside and outside class.