Lesbian and gay (LG) individuals are perceived as having poorer relationship functioning than heterosexual individuals, but this negative appraisal is not translated into actual relationship experiences. Indeed, relationship quality outcomes do not vary according to sexual orientation. Cohabitation status may play an important role, because it symbolizes relationship commitment and intimacy particularly for LG individuals. A cross-sectional study (N = 425, 52.9% women; Mage = 28.38, SD = 6.89) with romantically involved LG (38.4%) and heterosexual (61.6%) individuals examined the association between cohabitation and relationship quality outcomes. To isolate the role of cohabitation, cohabiting individuals were compared according to relationship legal status. Results showed that cohabiting (vs. non-cohabiting) LG individuals were more committed, invested, and satisfied, but those who legalized (vs. did not legalize) their union were only more committed. Among heterosexual individuals, no differences were observed. Furthermore, LG (vs. heterosexual) individuals were overall more committed, satisfied, and invested when cohabiting with their partner (especially in legalized unions), whereas heterosexual (vs. LG) individuals were more committed in non-cohabiting relationships. No other differences were found. This suggests that cohabitation may be used by LG individuals as a strategy to strengthen relationship quality and that legal recognition further increases relationship commitment.