This study investigated how interlocutors’ linguistic competence affected L2 speakers’ lexical alignment and how the interlocutor effect was modulated by speakers’ proficiency. Chinese English as a Foreign Language speakers performed an online text-based picture-naming and -matching task with interlocutors of different perceived linguistic competences: an L1 interlocutor, an L2 interlocutor of higher proficiency or an L2 interlocutor of lower proficiency. We compared the magnitudes of L2 speakers’ lexical alignment across interlocutor conditions and examined whether the interlocutor effect varied with speakers’ L2 proficiency. Results showed that L2 speakers aligned more with the L1 interlocutor than the L2 interlocutor, indicating an effect of interlocutors’ language status (native vs. non-native). Moreover, L2 speakers’ lexical alignment with interlocutors of varying proficiency was differentially affected by their own proficiency levels. This study adds to the existing work by revealing the joint influence of the interlocutors’ competence and the speakers’ L2 proficiency on lexical alignment in L2 communication.