Background: Ocrelizumab is an approved intravenously administered anti-CD20 antibody for multiple sclerosis (MS). Shortening the 600 mg infusion to 2 hours reduces the total site stay from 5.5–6 hours (approved infusion duration including mandatory pre-medication and post-infusion observation) to 4 hours. The safety profile of shorter-duration ocrelizumab infusions was investigated using results from ENSEMBLE PLUS. Methods: ENSEMBLE PLUS is a randomized, double-blind substudy to the single-arm ENSEMBLE study (NCT03085810). In ENSEMBLE, patients with early-stage relapsing-remitting MS received ocrelizumab 600 mg infusions every 24 weeks for 192 weeks. In ENSEMBLE PLUS, ocrelizumab 600 mg administered over the approved 3.5-hour infusion time (conventional duration) is compared with a 2-hour infusion (shorter duration); the durations of the initial infusions (2×300 mg, 14 days apart) were unaffected. The primary endpoint was the proportion of patients with infusion-related reactions (IRRs) following the first Randomized Dose. Results: From November 1, 2018, to December 13, 2019, 745 patients were randomized 1:1 to the conventional or shorter infusion group. At the first Randomized Dose, 99/373 patients (26.5%) in the conventional and 107/372 patients (28.8%) in the shorter infusion group experienced IRRs. The majority of IRRs were mild or moderate; >99% of all IRRs resolved without sequelae in both groups (conventional infusion group, 99/99; shorter infusion group, 106/107). No IRRs were serious, life-threatening, or fatal. No IRR-related discontinuations occurred. During the first Randomized Dose, 22/373 (5.9%) and 39/372 (10.5%) patients in the conventional and shorter infusion groups, respectively, had IRRs leading to infusion slowing/interruption. Adverse events were consistent with the known safety profile of ocrelizumab. Conclusion: The rates and severity of IRRs were similar between conventional and shorter infusions. No new safety signals were detected. Shortening the infusion time to 2 hours reduces the total site stay time (including mandatory pre-medication/infusion/observation) from 5.5–6 hours to 4 hours, and may reduce patient and site staff burden. A short video summarizing the key results is provided in supplemental material.