The COVID-19 pandemic has provided second language (L2) learners with additional challenges regarding how to obtain an enjoyable experience while achieving a better learning attainment. Despite a growing body of studies that substantiated the predictive effect of grit, foreign language enjoyment (FLE), and foreign language classroom anxiety (FLA) on Chinese language achievement (CLA), no previous research has explored their predictive effects in online L2 Chinese learning. To address this gap, this study clarifies the nature of the complex correlation between grit, FLE, FLA, and online CLA by analyzing 169 responses from Arabic multilingual learners using structural equation modelling. The results indicate that: (i) FLE, not FLA, significantly predicts online L2 CLA; (ii) FLE acts as a positive mediator between grit and online L2 CLA; and (iii) FLE has a stronger impact in catalyzing an individual's online L2 success. This study enriches the applicability of the broaden-and-build and control-and-value theories in the field of Chinese language learning. We hope that this study will serve as a call for further attention to emotions and grit, especially for languages other than English, in order to advance the growth of positive psychology in L2 learning and teaching.