The purpose of this descriptive study is to investigate on-line learning readiness levels of student teachers according to several variables. By using purposive sampling method, the sample consisted of 270 (200 female and 70 male) student teachers in Turkey. Data collection tools include (i) Student Demographics Form with 18 items, (ii) On-line Learning Readiness Scale with 18 items and five factors. Statistically, the quantitative data were analyzed via ANOVA, t-test and ANCOVA. The findings suggest that mean of on-line learning readiness levels of student teachers is at good level. On-line learning readiness levels of student teachers are significantly different according to their departments [F(4,265)=3.450, p=0.09]. Namely, the mean scores for the students from Elementary Education and Pre-school Education departments were significantly higher than those from Social Science Education department. Besides, student teachers who has Internet access had higher on-line learning readiness scores (M= 67.27, SD=9.86) than did those without access (M= 60.14, SD=10.64), t(268)=3.16, p=0.002. There are also significant differences between student teachers' on-line learning readiness scores per their perceived information and communication technology use competency and departments after differences in accessibility to the Internet is controlled (p<0.001). As mentioned by International Society for Technology in Education in 2019 standards, on-line learning readiness needs to be considered in detail to assist learners in using digital media in 21st century for learning; teaching; gathering, producing, sharing information for educational purposes. In conclusion, it is suggested that practitioners should increase online, distance or blended (both on-line and face-to-face) learning experiences of their students who are prospective teachers of the 21st century learners. Therefore, it is strongly suggested contributing development of learning and teaching skills of student teachers by getting them more familiar with on-line learning environments especially in post-COVID times.