<p>Greater student belonging is linked to improved academic, social, and health outcomes and could help reduce loneliness and its associated health risks. The need for belonging is especially critical for emerging adults, who are navigating instability in relationships and commitments while exploring their identities, building skills for connection, and broadening their social worlds. Helping students reflect on and adapt to ambiguous environmental cues and social interactions, as well as accept negative feelings and work through them in alignment with their valued goals, could strengthen their sense of belonging. Psychological flexibility – one’s ability to be present and open without defenses to thoughts and feelings and to behave based on personal values – is a modifiable capacity that is understudied in relation to belonging. Using cross-sectional survey data from over 16,000 undergraduate students in 104 U.S. colleges and universities, we examined the association between psychological flexibility and students’ sense of belonging. After adjusting for covariates, higher psychological flexibility was significantly associated with greater belonging. For each 1 SD increase in the psychological flexibility score, there was a 0.43 (95% CI: 0.40, 0.45) unit increase in the adjusted belonging <i>z</i> score (<i>P</i> &lt; .001). Efforts by colleges and universities to increase students’ psychological flexibility, alongside ongoing efforts to make students feel accepted, valued, and connected, could improve student belonging and its associated benefits.</p>