Transanal total mesorectal excision (TaTME) is a novel technique that overcomes the problem of access to the deep pelvis during radical surgery for mid-rectal and lower rectal cancer. Although TaTME has several important steps, the creation of the distal purse-string suture following TaTME plays an important role in ensuring the integrity of the colorectal anastomosis. However, this procedure represents a major technical challenge for the surgeon. Robot-assisted surgery may make this suturing procedure easier than laparoscopic surgery because it permits intuitive wrist movements and a three-dimensional view. The aim of the present study was to investigate the usefulness of transabdominal robotic purse-string suture during anastomosis in TaTME. Twenty-seven patients, who underwent anastomosis using a single stapling technique (SST) during the TaTME of mid-rectal or lower rectal cancer, were enrolled in the study. The patients were allocated to two groups: 11 patients underwent transabdominal robotic purse-string suturing (the Robot group) and 16 patients underwent transanal purse-string suturing (the Transanal group). The characteristics and short-term surgical outcomes of the participants were compared between the two groups. The Robot group tended to have a shorter purse-string suturing time (541 ± 206 seconds versus 729 ± 310 seconds; P = .07). Regarding the shape of the "donut" after SST anastomosis, in the Transanal group, 5 of the 16 participants had incomplete donuts with muscular defects and required additional suturing, whereas in the Robot group, all the participants had complete donuts (P = .04). Transabdominal robotic purse-string suturing may facilitate the suturing procedure and contribute to reliable anastomosis.