There is a wealth of research investigating language learners' adoption of digital technology in higher education. To date, however, research primarily focuses on the implementation of technology in formal learning either inside or outside of the classroom, and the associations between factors influencing learners' informal English learning in online contexts are not adequately discussed. Therefore, the present study aims to identify and test the main factors related to students' informal online English learning (IOEL) that could predict their usage intention. To better understand the drivers of technology use for informal L2 learning among university students, this study proposed a model based on the Technology Acceptance Model (TAM) to investigate students' behavioural intention toward IOEL with particular reference to Malaysian L2 learners. The partial least square approach of the structural equation modelling (PLS-SEM) was applied to test the proposed research model and the corresponding hypotheses. The results indicate that nine out of ten of the hypotheses were supported, which implies that the extended model can effectively predict L2 learners' IOEL technology adoption in online contexts. The results also showed that perceived interaction and perceived ease of use were the two main predictors influencing learner's technology acceptance for IOEL.