Idecabtagene vicleucel (ide-cel) was the first FDA-approved chimeric antigen receptor T-cell therapy for relapsed/refractory multiple myeloma (RRMM) patients. This was the first study to evaluate patient-reported outcomes (PROs) among RRMM patients receiving ide-cel in standard of care (SOC). We prospectively assessed health-related quality of life (HRQOL) and symptoms from pre-infusion (baseline) through day (D)90 post-infusion. Baseline PRO associations with patient characteristics, mean PRO changes, and time to stable change were evaluated with t-tests, linear mixed-effects models, and Kaplan–Meier analyses, respectively. Within-person change scores and minimally important difference thresholds determined clinical and meaningful significance. Participants (n = 42) were a median of 66 years old (range: 43–81). At baseline, extramedullary disease was associated with worse physical well-being (p = 0.008), global pain (p < 0.001), performance status (p = 0.002), and overall symptom burden (p < 0.001). Fatigue (p < 0.001) and functional well-being (p = 0.003) worsened by D7 before returning to baseline levels. Overall HRQOL (p = 0.008) and physical well-being (p < 0.001) improved by D60. Most participants reported PRO improvement (10–57%) or maintenance (23–69%) by D90. The median time it took to stabile deterioration in functional well-being was 14 days. The median time it took to stabile improvement in physical and emotional well-being was 60 days. Overall, RRMM patients reported improvements or maintenance of HRQOL and symptom burden after SOC ide-cel.