Septins are highly conserved GTP-binding proteins that assemble into diverse hetero-oligomeric structures and associate with cellular membranes, particularly those with micron-scale curvature. While their role in cytokinesis is well established, septins also participate in a wide range of cellular processes, including neuronal morphogenesis, ciliogenesis, infections and spermiogenesis. In budding and fission yeast, septins have well characterized functions in cytokinesis and sporulation. Evidence also suggests a role for septins during cell fusion in budding yeast, whereas their contribution to this process in fission yeast remains largely unexplored. In this study, we investigate the role of septins during cell fusion in fission yeast using cell-biological approaches, super-resolution microscopy, expansion microscopy and genetic analysis of septin mutants. We show that the vegetatively expressed septins Spn1-Spn4, accumulate at the cell-cell contact site before fusion, where they form an hourglass-like structure, that rapidly reorganizes into a ring after fusion. Super-resolution and expansion microscopy further reveal the colocalization of septin subunits and their striped organization at the fusion site. Moreover, septin mutants display a reduced conjugation bridge width and delayed fusion pore expansion. Together, these findings suggest that septins contribute to the post-fusion expansion of the fusion pore in fission yeast, potentially through their dynamic reorganization at the cell-cell contact site.