Intersphincteric resection (ISR) with coloanal anastomosis is an oncologically safe anus-preserving technique for very low-lying rectal cancers. Most studies focused on oncological and functional outcomes of ISR with very few evaluating long-term postoperative anorectal complications. Full-thickness prolapse of the neorectum is a relatively rare complication. This report presents the case of a 70-year-old woman presenting with full-thickness prolapse of the side limb of the side-to-end coloanal anastomosis occurring 2 weeks after the stoma closure and 2 months after a robotic partial ISR performed with the Da Vinci single-port platform. The anastomosis was revised through resection of the side limb and conversion of the side-to-end anastomosis into an end-to-end handsewn anastomosis with interrupted stitches. This study describes the first case of full-thickness prolapse of the side limb of the side-to-end handsewn coloanal anastomosis following ISR. Moreover, a revision of all reported cases of post-ISR full-thickness and mucosal prolapse was performed.