Purpose: To examine known-groups validity of the Patient-Reported Outcomes Measurement Information System (PROMIS®) Short Forms (SFs) for adolescents and young adults with special healthcare needs (SHCN) using data collected from the PROMIS Linking Study. Methods: In total, 292 adolescents aged 14–17.9 years and 300 young adults aged 18–20 years with SHCN from the PROMIS Linking Study were used for analyses. Presence of SHCN was classified into three categories (medication use, service use, and functional limitations). HRQoL was measured with the PROMIS Pediatric and Adult SFs. Differences in health-related quality of life (HRQoL) domain scores between SHCN sample and the norms of the PROMIS pediatric and adult calibration samples, respectively, were compared using t tests. Associations of HRQoL scores with the presence of individual SHCN categories were tested using linear regression. Results: All HRQoL domain scores for the SHCN samples were significantly worse than the respective calibration samples. Adolescents and young adults with SHCN-related service use and functional limitations reported worse HRQoL than those without service use and functional limitations (p’s < 0.01). Conclusions: PROMIS Pediatric and Adult SFs possess satisfactory known-groups validity related to SHCN status.