Sickle cell disease significantly impacts one's quality of life (QOL); thus, randomized controlled trials (RCTs) have integrated patient-reported outcomes (PROs) to assess patients' health from their perspective. We aim to evaluate the completeness of reporting of PROs included in sickle cell disease RCTs. We searched MEDLINE, Embase and Cochrane Central Register of Controlled Trials (CENTRAL) for published sickle cell disease RCTs with at least one PRO measure from 2006 to 2021. In a masked, duplicate fashion, two investigators evaluated RCTs using the Consolidated Standards of Reporting in Trials (CONSORT)-PRO adaptation and Cochrane Collaboration Risk of Bias (RoB) 2.0 tool. The primary objective was mean percent completeness of the CONSORT-PRO adaptation. Additional relationships between trial characteristics and completeness of reporting were evaluated. Mean completeness of reporting of RCTs was 41.49% (SD = 20.90). Randomized controlled trials with primary outcomes were more complete (57.50%, SD = 8.33) than RCTs with secondary PROs (33.48%, SD = 20.91). We did not find a significant difference in completion between trials with primary PROs and secondary PROs (t1 = 2.07; p = 0.06). Our secondary objectives included factors that may be associated with completeness of PRO reporting. Of the 12 included studies, five were considered to be overall 'high' RoB (41.67%). In each of the five domains, the majority of studies received 'low' RoB evaluations. Incomplete PRO reporting was common within sickle cell RCTs. Therefore, we recommend future RCTs including PROs should take measures to increase completeness of reporting.