The potential impact of abdominal wound dehiscence on long-term survival after elective abdominal surgery is largely unknown. The aim of this study was to examine the impact of abdominal wound dehiscence on survival and incisional hernia repair after elective, open colonic cancer resection. This was a nationwide cohort study based on merged data from Danish national registries, comprising patients subjected to elective, open resection for colonic cancer between May 1, 2001 and January 1, 2016. Multivariable Cox Regression analysis and propensity score matching was applied to adjust for confounding. The associations of abdominal wound dehiscence with 90-day mortality and subsequent incisional hernia repair were also examined. A total of 14,169 patients were included in the cohort, of which 549 (3.9%) developed abdominal wound dehiscence. The 5-year survival was significantly decreased in patients with abdominal wound dehiscence (42.4%, 95% CI 38.1-46.7 vs. 53.4%, 52.6-54.3, P < 0.001), which was confirmed in the multivariable analysis (HR 1.22, CI 1.06-1.39, P = 0.004). Abdominal wound dehiscence was significantly associated with increased risk of 90-day mortality (OR 1.60, CI 1.12-2.27, P = 0.009) as well as subsequent incisional hernia repair (HR 1.80, CI 1.07-3.01, P = 0.026). Abdominal wound dehiscence was significantly associated with decreased survival. Fascial closure after open colonic cancer resection should be given high priority to improve the long-term survival.