Introduction: The growing population of survivors following pediatric surgery emphasizes the importance of long-term follow-up. The impact of surgical scars on daily life can be evaluated through patient-reported outcome measurements. The Stony Brook Scar Evaluation Scale (SBSES) and SCAR-Q questionnaire are two interesting instruments for this purpose. We evaluated their psychometric performance in Dutch children after pediatric surgery. Methods: After English–Dutch translation, we evaluated—following the COSMIN guidelines—the feasibility, reliability (internal and external), and validity (construct, criterion, and convergent) of the SBSES and SCAR-Q in Dutch patients < 18 years old with surgical scars. Results: Three independent observers completed the SB for 100 children (58% boys, median age 7.3 (IQR 2.5–12.1) years) in whom surgery had been performed a median of 2.8 (0.5–7.9) years ago. Forty-six of these children (61% boys, median age 12.1 (9.3–16.2) years) completed the SCAR-Q. Feasibility and internal reliability (Cronbach’s alpha > 0.7) was good for both instruments. For the SB, external reliability was poor to moderate (interobserver variability: ICC 0.46–0.56; intraobserver variability: ICC 0.74). For the SCAR-Q, external reliability was good (test–retest agreement: ICC 0.79–0.93). Validity tests (construct, criterion, and convergent) showed poor to moderate results for both instruments. Conclusions: The Dutch-translated SBSES and SCAR-Q showed good feasibility and internal reliability. External reliability and validity were likely affected by differences in conceptual content between the questionnaires. Combining them would provide insight in the impact of scars on patients. Implementation of these instruments in longitudinal follow-up programs could provide new insights into the long-term psychological outcome after pediatric surgery.