Purpose <p>Kidney transplantation (KT) is associated with better clinical and health-related quality of life (HRQOL) outcomes than dialysis. However, some KT recipients (KTRs) live with poor kidney function (eGFR ≤ 29&#xa0;ml/min/1.73&#xa0;m²). We use the Patient-Reported Outcomes Measurement Information System (PROMIS^®) Physical Health (PHS) and Mental Health (MHS) Summary Scores to compare HRQOL between patients on dialysis versus KTRs with either poor (eGFR ≤ 29&#xa0;ml/min/1.73m²) or preserved (eGFR &gt; 29&#xa0;ml/min/1.73&#xa0;m²) kidney function.</p> Methods <p>Secondary analysis of cross-sectional data from a convenience sample of adults treated with dialysis or KT. Exposure: kidney replacement therapy (KRT) type. Outcome: PHS and MHS scores. The PHS and MHS structural validity, test-retest reliability, correlations with legacy measures, and known-group comparisons were evaluated. The independent association between HRQOL and KRT was assessed using multivariable linear regression.</p> Results <p>Of the 647 participants, 388 (60%) were male, the mean (standard deviation [SD]) age was 57 (16) years, and 367 (57%) were KTRs. Our results supported structural and construct validity and test-retest reliability of PROMIS PHS and MHS. KTRs had significantly better PHS compared to dialysis (adjusted mean [95% CI]: 46.6[45.6; 47.6] versus 39.5[38.4; 40.8], <i>p</i> &lt; 0.001), and also better MHS (50.9[49.8; 51.9] versus 46.6[45.4; 47.9], <i>p</i> &lt; 0.001). However, KTRs with eGFR ≤ 29&#xa0;ml/min/1.73&#xa0;m² (9% of all KTRs) had similar PHS and MHS compared to dialysis. Certain clinical variables were associated with HRQOL among KTRs, but not in patients on dialysis nor in KTRs with eGFR ≤ 29&#xa0;ml/min/1.73&#xa0;m².</p> Conclusion <p>HRQOL is better among KTRs than among patients on dialysis, but not in KTRs with poor kidney function.</p>