IMPORTANCE: The variability in individual symptom and adverse event reporting between pediatric patient-reports and proxy-reports is widely reported. However, the question of whether symptom profiles based on reports from children with cancer and their caregivers are similar or disparate have not yet been studied. OBJECTIVE: To compare proxy symptom reports with patient self-reports to assess alignment. DESIGN, SETTING, AND PARTICIPANTS: A multicenter cohort study was conducted from October 2016 to December 2018 from data collected at 9 pediatric cancer centers. Participants were a convenience sample of family caregivers or proxies of children aged 7 to 18 years who had received disease-directed oncology treatment in the form of chemotherapy for at least 1 month. Data were analyzed identifying clusters of individuals (ie, latent profiles) based on various responses (ie, indicators) in August 2021. EXPOSURES: The children of proxy participants received upfront chemotherapy. Children and proxies completed Patient-Reported Outcomes Measurement Information System (PROMIS) surveys at 2 time points: within 72 hours preceding treatment initiation and following the course of chemotherapy. MAIN OUTCOMES AND MEASURES: The latent profile analysis methods were applied to caregiver-proxy reports of PROMIS Pediatric symptom and function measures (anxiety, depressive symptoms, pain interference, fatigue, psychological stress, and physical function-mobility). The instrument categorized respondents as high symptom suffering, medium symptom suffering, and low symptom suffering (hereafter, high, medium, and low symptom groups, respectively). RESULTS: Of 580 approached proxies, 431 (368 [85.00%] were female) identified as legal guardians of children aged 7 to 18 years with a first cancer diagnosis (mean [SD] age, 13.03 [3.40] years; 235 [54.65%] were male). Proxy reports of children's experiences based on the 5 proxy PROMIS measures comprised 3 distinct symptom profiles. The most common proxy assessments of children's experiences were the moderate symptom groups (45.7% [197 of 431]) and the low symptom groups profiles (40.1% [173 of 431]). A high symptom groups profile emerged which represented 14.2% (61 of 431) of proxy assessments. The number of profiles and observed distribution of profile membership was similar between child and proxy reports. Proxy reports of individual symptoms generally recorded higher scores than child reports; however, no significant difference was observed between proxies and child profile model results for the PROMIS measures. CONCLUSIONS AND RELEVANCE: Results of this cohort study suggest that, at the level of symptom severity profile, proxy caregiver reports may approximate the children's reports and may serve as a guide to care when the child is not able to self-report.