This study investigated the sociolinguistic pragmatic performance of eight advanced Chinese learners from a variationist sociolinguistic perspective, focusing on the variable appearance versus absence of Mandarin sentence final particles (SFPs) in non-interrogative sentences. These learners participated in a Chinese TV talk show and have become popular on social media platforms. The speech data from the talk show (400 tokens) and online data from Chinese social media platform Weibo (400 tokens) were collected and analyzed. These Chinese L2 users productively demonstrated variation in their use of SFPs in non-interrogative sentences, in that they added SFPs to a sentence in around 20% of variable contexts. Rbrul (logistic regression) analyses revealed that the variable presence of SFPs was conditioned by their duration of time spent in China and gender-related personalities. Follow-up case analyses explored how they made use of SFPs in different situations and how they were received by other participants. The study found that these Chinese L2 users became active social agents who made decisions to shift styles in different contexts or to strengthen their identities. The results are discussed within a broader context of identity, language socialization, and L2 social agency. This study also attempts to offer pedagogical implications for the acquisition of Chinese SFPs.