Despite the growing prevalence of adult congenital heart disease (ACHD), data on trends in prevalence of mental health disorders (MHD) among patients with ACHD remain limited. The National Inpatient Sample (2007 to 2014) was queried to identify the frequency and trends of MHD among ACHD hospitalizations (stratification by age, sex, and race); demographics and co-morbidities for ACHD cohorts, with (MHD+) versus without MHD (MHD-); the rate and trends of all-cause in-hospital mortality, disposition, mean length of stay, and hospitalization charges among both cohorts. A total of 11,709 (13.8%, mean age: 49.1 years, 56.0% females, 78.7% white) out of 85,029 ACHD patient encounters had a coexistent MHD (anxiety, depression, mood disorder, or psychosis). ACHD-MHD+ cohort was more often admitted nonelectively (38.1% vs 32.8%, p <0.001) and had a higher frequency of cardiac/extra-cardiac co-morbidities. The trends in prevalence of coexistent MHD increased from 10.3% to 17.5% (70% relative increase) from 2007 to 2014 with a consistently higher prevalence among females (from 13% to 20.3%) compared to males (from 7.6% to 15.5%) (p_trend <0.001). The hospitalization trends with MHD increased in whites (12.1% to 19.8%) and Hispanics (5.9% to 12.7%). All-cause mortality was lower (0.7% vs 1.1%, p = 0.002) in ACHD-MHD+; however, mean length of stay (∼5.7 vs 4.9 days, p <0.001) was higher without significant difference in charges ($97,710 vs $96,058, p = 0.137). ACHD-MHD+ cohort was less often discharged routinely (declining trend) and more frequently transferred to other facilities and required home healthcare (rising trends). In conclusion, this study reveals increasing trends of MHD, healthcare resource utilization and a higher frequency of co-morbidities in patients with ACHD.