ImportanceEmployment is an important factor in quality of life and provides social and economic support. Longitudinal data on employment and associations with chronic health conditions for adult survivors of childhood cancer are lacking.ObjectiveTo evaluate longitudinal trends in employment among survivors of childhood cancer.Design, Setting, and ParticipantsRetrospective cohort study of 5-year cancer survivors diagnosed at age 20 years or younger between 1970 and 1986 enrolled in the multi-institutional Childhood Cancer Survivor Study (CCSS). Sex-stratified employment status at baseline (2002 to 2004) and follow-up (2014 to 2016) was compared with general population rates from the Behavioral Risk Factor Surveillance System cohort. Data were analyzed from July 2021 to June 2022.ExposuresCancer therapy and preexisting and newly developed chronic health conditions.Main Outcomes and MeasuresStandardized prevalence ratios of employment (full-time or part-time, health-related unemployment, unemployed, not in labor force) among adult (aged ≥25 years) survivors between baseline and follow-up compared with the general population. Longitudinal assessment of negative employment transitions (full-time to part-time or unemployed at follow-up).ResultsFemale participants (3076 participants at baseline; 2852 at follow-up) were a median (range) age of 33 (25-53) years at baseline and 42 (27-65) years at follow-up; male participants (3196 participants at baseline; 2557 at follow-up) were 33 (25-54) and 43 (28-64) years, respectively. The prevalence of full-time or part-time employment at baseline and follow-up was 2215 of 3076 (71.3%) and 1933 of 2852 (64.8%) for female participants and 2753 of 3196 (85.3%) and 2079 of 2557 (77.3%) for male participants, respectively, with declining standardized prevalence ratios over time (female participant baseline, 1.01; 95% CI, 0.98-1.03; follow-up, 0.94; 95% CI, 0.90-0.98; P < .001; male participant baseline, 0.96; 95% CI, 0.94-0.97; follow-up, 0.92; 95% CI, 0.89-0.95; P = .02). While the prevalence of health-related unemployment increased (female participants, 11.6% to 17.2%; male participants, 8.1% to 17.1%), the standardized prevalence ratio remained higher than the general population and declined over time (female participant baseline, 3.78; 95% CI, 3.37-4.23; follow-up, 2.23; 95% CI, 1.97-2.51; P < .001; male participant baseline, 3.12; 95% CI, 2.71-3.60; follow-up, 2.61; 95% CI, 2.24-3.03; P = .002). Among survivors employed full-time at baseline (1488 female participants; 1933 male participants), 285 female participants (19.2%) and 248 male participants (12.8%) experienced a negative employment transition (median [range] follow-up, 11.5 [9.4-13.8] years). Higher numbers and grades of chronic health conditions were significantly associated with these transitions.Conclusions and RelevanceIn this retrospective analysis of adult survivors of childhood cancer, significant declines in employment and increases in health-related unemployment among cancer survivors compared with the general population were identified. A substantial portion of survivors in the midcareer age range fell out of the workforce. Awareness among clinicians, caregivers, and employers may facilitate clinical counseling and occupational provisions for supportive work accommodations.