OBJECTIVE: Prematurity and low birth weight (LBW) are risk factors for increased morbidity and mortality in infants with congenital heart defects (CHDs). We sought to describe survival, inhospital morbidities, and 2-year neurodevelopmental follow-up in LBW infants with CHD. STUDY DESIGN: We included infants with birth weight (BW) <2,500 g diagnosed with CHD (except isolated patent ductus arteriosus) admitted January 2013 to March 2016 to a single level-IV academic neonatal intensive care unit. We reported CHD prevalence by BW and gestational age; selected in-hospital morbidities and mortality by infant BW, CHD type, and surgical intervention; and developmental outcomes by Bayley's scales of infant and toddler development, third edition (BSID-III) scores at age 2 years. RESULTS: Among 420 infants with CHD, 28 (7%) underwent cardiac surgery. Median (25th and 75th percentiles) gestational age was 30 (range: 27-33) weeks and BW was 1,258 (range: 870-1,853) g. There were 134 of 420 (32%) extremely LBW (<1,000 g) infants, 82 of 420 (20%) were small for gestational age, and 51 of 420 (12%) multiples. Most common diagnosis: atrial septal defect (260/420, 62%), followed by congenital anomaly of the pulmonary valve (75/420, 18%). Most common surgical procedure: pulmonary artery banding (5/28, 18%), followed by the tetralogy of Fallot corrective repair (4/28, 14%). Survival to discharge was 88% overall and lower among extremely LBW (<1,000 g, 81%) infants and infants undergoing surgery (79%). Comorbidities were common (35%); retinopathy of prematurity and bronchopulmonary dysplasia were most prevalent. BSID-III scores were available on 148 of 176 (84%); any scores <85 were noted in 73 of 148 (49%), with language being most commonly affected. CONCLUSION: Among LBW infants with congenital heart disease, hospital mortality varied by BW and cardiac diagnosis. KEY POINTS: · In low birth weight infants with congenital heart disease, survival varied by birth weight and cardiac diagnosis.. · Overall survival was higher than previously reported.. · There were fewer morbidities than previously reported.. · Bayley's scale-III scores at 2 years of age were <85 for nearly half..