Purpose: Patient-reported outcomes (PRO) were evaluated in the phase III IMmotion151 trial (NCT02420821) to inform overall treatment/disease burden of atezolizumab plus bevacizumab versus sunitinib in patients with previously untreated metastatic renal cell carcinoma (mRCC). Patients and Methods: Patients were randomized 1:1 to receive atezolizumab 1,200 mg intravenous (i.v.) infusions every 3 weeks (q3w) plus bevacizumab 15 mg/kg i.v. q3w or sunitinib 50 mg per day orally 4 weeks on/2 weeks off. Patients completed the MD Anderson Symptom Inventory (MDASI), National Comprehensive Cancer Network Functional Assessment of Cancer Therapy-Kidney Symptom Index (FKSI-19), and Brief Fatigue Inventory (BFI) at baseline, q3w during treatment, at end of treatment, and during survival follow-up. Longitudinal and time to deterioration (TTD) analyses for core and RCC symptoms and their interference with daily life, treatment side-effect bother, and health-related quality of life (HRQOL) were evaluated. Results: The intent-to-treat population included 454 and 461 patients in the atezolizumab plus bevacizumab and sunitinib arms, respectively. Completion rates for each instrument were 83% to 86% at baseline and ≥ 70% through week 54. Milder symptoms, less symptom interference and treatment side-effect bother, and better HRQOL at most visits were reported with atezolizumab plus bevacizumab versus sunitinib. The TTD HR (95% CI) favored atezolizumab plus bevacizumab for core (HR, 0.50; 0.40–0.62) and RCC symptoms (HR, 0.45; 0.37–0.55), symptom interference (HR, 0.56; 0.46–0.68), and HRQOL (HR, 0.68; 0.58–0.81). Conclusions: PROs in IMmotion151 suggest lower overall treatment burden with atezolizumab plus bevacizumab compared with sunitinib in patients with treatment-naïve mRCC and provide further evidence for clinical benefit of this regimen.