Background: Long-term outcomes are not well established at the population level after completion of the total cavopulmonary connection (TCPC) among patients with functional univentricular hearts. Purpose: To evaluate the incidence of cardiovascular events after TCPC completion. Methods: From a validated population-based cohort, we identified 178 patients with TCPC circulation completed after January 1, 1995. We established a comparison cohort by frequency-matching patients 1:200 on sex, and month and year of birth to the general Danish population (n = 35,600 population controls). We started follow-up at date of TCPC completion for cases and, for controls, at the index date of their matched case. The risks of cardiovascular events were assessed using cumulative incidence rates and Poisson regression models adjusted for age, sex, and calendar year. Results: The median age at TCPC completion was 3.3 years (interquartile range 2.6 to 5.3 years). Over a median follow-up of 12.5 years, 10 (5.6%) TCPC patients died and 7 (4.5%) had a heart transplantation compared with a 0.2% mortality in the matched population. In TCPC patients, 15.7% had an arrhythmia (11.8% supraventricular tachycardia), 3.4% had a stroke (all ischemic), and 21.4% of TCPC patients initiated a combination of a diuretic and a renin-angiotensin system (RAS)-inhibitor. These rates were >50-fold higher than in the comparison cohort: 0.2% arrhythmia, 0.06% stroke, and 0.04% starting a diuretic and a RAS-inhibitor. Conclusions: Patients with TCPC circulation face a high risk of cardiovascular events during intermediate term follow-up.