Learning a foreign language is a long-term process requiring persistence and a willingness to engage in activities that will help develop communicative competence. An important role on the way to achieving linguistic proficiency is played by L2 grit. However, foreign language learners differ in the intensity of this trait. We identify the most important predictors of L2 grit in the online language learning context. Basing on a literature review, we first identify possible predictors in the generic process of L2 learning, including language mindsets as well as two general psychological dispositions: a sense of autonomy and curiosity, and subsequently one predictor specifically related to the virtual learning context, i.e., readiness for online learning. A multiple linear regression model built using questionnaire data collected from 615 learners from 69 countries enrolled in language courses taught in a remote or hybrid mode reveals that L2 grit is most determined by two dimensions of readiness for online learning, and to a lesser extent by learners' autonomy and curiosity, and significantly and positively correlates with these factors. The regression model explains 48% of variance in the dependent variable. A subsequent psychological network analysis, one of the first applications of this method in the field of SLA, permitted estimating the relative importance of these factors in the complex network of associations, indicating equally strong direct connections between L2 grit and both dimensions of readiness for online learning, and a much weaker edge linking L2 grit with autonomy. The findings have practical implications for language teachers in remote and hybrid settings.