The primary purpose of this study was to investigate the mediating effects of second language (L2) motivation, willingness to communicate (WTC), and international posture on the relationship between L2 Self-perceived communication competence (SPCC) and L2 frequency of communication (L2 FC) in online informal English learning contexts among tertiary students in Malaysia. The predictor variables were drawn from Gardner's (1985) socio-educational model of language learning and MacIntyre and Charos' (1996) WTC model and adapted to examine the frequency of communication in online contexts. A total of 296 valid responses were collected from university students in Malaysia. The data were collected using online survey and were analysed through partial least squares structural equation modelling (PLS-SEM) technique. The findings suggested that higher level of L2 SPCC would lead to more frequent L2 use in online contexts. Furthermore, the mediating roles of L2 WTC and international posture were found to be statistically significant. However, the mediating effect of L2 motivation on the relationship between L2 SPCC and communication frequency was not supported in this study. Implications of the research findings for understanding the relationship among the study's variables are also discussed.