Importance: Childhood cancer survivors may be reluctant to make changes in their employment because of access to health insurance. Objective: To examine the prevalence of "job lock" (staying at a job to keep work-related health insurance) in a sample drawn from an established, multi-institutional cohort of full-time employed childhood cancer survivors compared with a random sample of siblings and to explore factors associated with job lock among cancer survivors. Design, Setting, and Participants: Cross-sectional survey of full-time employed adult survivors of childhood cancer and a random sample of siblings derived from a cohort of 25 US pediatric oncology centers. Exposures: Data collection included sociodemographic factors, insurance coverage, chronic medical conditions, and treatment. Main Outcomes and Measures: Self-report of job lock and factors associated with job lock. Results: Among the 522 participants, 394 were cancer survivors (54.5% male) and 128 were siblings (51.5% male). Job lock was reported by 23.2% (95% CI, 18.9%-28.1%) of survivors, compared with 16.9% (95% CI, 11.1%-25.0%) of siblings (P = .16). Job lock was more common among survivors reporting previous health insurance denial (relative risk [RR], 1.60; 95% CI, 1.03-2.52) and problems paying medical bills (RR, 2.43; 95% CI, 1.56-3.80). Among survivors, being female (RR, 1.70; 95% CI, 1.11-2.59; P = .01) and having a severe, disabling, or life-threatening health condition (RR, 1.72; 95% CI, 1.09-2.69; P = .02) were associated with job lock. Conclusions and Relevance: Job lock is common among long-term childhood cancer survivors who are employed full-time. A survivor's decision to remain employed at a job in order to maintain health insurance coverage may affect career trajectory, diminish potential earning power, and ultimately impact quality of life.