Purpose <p>Despite recent advances in multimodal treatment strategies, radical tumor resection remains a cornerstone in the management of patients with rectal cancer. However, a substantial proportion of patients develop postoperative functional impairment known as low anterior resection syndrome (LARS). Emerging evidence suggests that robotic-assisted surgery may offer superior functional outcomes compared to other approaches. Therefore, this study aimed to compare the incidence and severity of LARS after robotic and open surgery using a patient-reported outcome measure (PROM).</p> Methods <p>This retrospective, single-center cohort study included patients with primary adenocarcinoma of the sigmoid colon or rectum who underwent open or robotic oncological resection between 2014 and 2024. Eligible participants completed a standardized, validated questionnaire to assess their individual LARS score. The LARS scores were subsequently correlated with selected clinicopathological characteristics.</p> Results <p>LARS questionnaires were analyzed in 184 patients. The incidence of major LARS was comparable between open and robotic surgery (39.1% vs. 39.2%), as was the rate of minor LARS (20% vs. 15%), with no statistically significant difference observed in multivariable ordinal regression (<i>p</i> = 0.451). Independent risk factors for LARS included neoadjuvant treatment, hand-sewn coloanal anastomosis, formation of a protective stoma, tumor location in the middle and lower rectum, and total mesorectal excision.</p> Conclusion <p>LARS remains a significant clinical challenge, irrespective of the surgical approach. This PROM-based finding is particularly relevant for preoperative counseling and shared decision-making, as it suggests that open surgery is not inherently associated with worse functional outcomes in terms of LARS. Future research should aim to identify the biological, anatomical, and clinical determinants underlying the variable susceptibility to LARS.</p>