In a secondary analysis of a randomized controlled trial (RCT), we examined participants' engagement with INSPIRE, a personalized online program for hematopoietic cell transplantation (HCT) survivors that focuses on cancer-related distress, depression, fatigue, and health care needs. We approached all adult, 3- to 18-year HCT survivors treated for hematologic malignancy without relapse or second cancer in the previous 2 years for participation in an RCT with either immediate or delayed access to INSPIRE. Participants with immediate access could view the online material at any time. Data included page view tracking, medical records, and patient-reported outcomes, including the Short Form 36 and Cancer and Treatment Distress (CTXD) measures. Of 1322 eligible HCT survivors, 771 (58%) completed the baseline assessment, and 451 received immediate INSPIRE access and were included in analyses. The cohort was 56% male, with a mean age of 52 ± 12.2 years, and 26% received an autologous transplant. Most (77%) logged into the INSPIRE site at least once, and 48% viewed ≥8 pages. Survivors who viewed ≥2 pages were more likely to be age ≥40 years (relative risk [RR], 1.41; 95% confidence interval [CI], 1.10 to 1.80), to be female (RR, 1.22; 95% CI, 1.07 to 1.40), to have chronic graft-versus-host disease (RR, 1.28; 95% CI, 1.08 to 1.51), to be less than 10 years post-HCT (RR, 1.19; 95% CI, 1.01 to 1.39), and to have moderate CTXD distress (RR, 1.34; 95% CI, 1.14 to 1.57). Engagement did not differ by race, education, income, rural/urban residence, computer experience, donor type, or depression (all P ≥ .50). The INSPIRE online program was widely used, including by those who often have reduced access to care after treatment.