Background: The surgical management of left-sided malignant large bowel obstruction (MLBO) is associated with high morbidity and mortality. Recently, self-expandable metallic colonic stent (SEMS) and transanal decompression tube (TDT) used as a 'bridge to surgery' (BTS) have been widely used. This study aims to compare the clinical outcomes and oncological safety of SEMS and TDT as BTS to transform MLBO into elective surgery. Methods: Between February 2013 and March 2019, 62 patients with MLBO received SEMS (n = 32) or TDT (n = 30), and elective one-stage surgery later. We evaluated decompression efficiency and oncological safety in selective operation in TDT and SEMS groups, including preoperative preparation time, surgical approach, number of lymphatic dissection and vascular invasion, ulcer formation and histopathological findings of resected specimens. Results: The preoperative preparation time in the SEMS group was shorter than that of the TDT group (P < 0.05). However, there was no significant difference between the groups in postoperative length of hospital stay (P > 0.05). The number of vascular invasions in the TDT group was less than that in the SEMS group (P < 0.05). Furthermore, the risk of wound abscess and ulcer formation in the TDT group was significantly lower than that in the SEMS group (P < 0.05). Conclusion: Our findings suggest that SEMS is associated with a relatively poor oncological outcome and the placement of TDT as BTS in MLBO patients may be a better alternation.