Using communication accommodation theory, this article examined how affective (i.e. identity linked) and cognitive (i.e. comprehension linked) motives drive young Swedish‐speaking Finns to employ Swedish in online communication when interacting with Finnish speakers. Questionnaire data were gathered amid Swedish‐speaking secondary school students (N = 124). A Bayesian mitigated mediation disclosed that the use of Swedish was guided both by cognitive and affective motives. Farther, affective motives were stronger predictors of language behaviour in cases where participants did not perceive they were limited by interlocutors' proficiency in Swedish. However, an analogous effect was not discovered for cognitive motives. Findings and their theoretical implications are debated with respect to bilingual accommodation.