In-hospital sudden cardiac arrests occurring during nighttime and weekend hours or within unmonitored hospital areas have been reported to have a poorer outcomes than monitored cardiac arrest. This study sought to assess the outcome of in-hospital ventricular tachycardia (VT) and ventricular fibrillation (VF) arrest by time of day, day of week, and within-hospital location when using a wearable cardioverter defibrillator (WCD). We retrospectively identified and reviewed consecutive in-hospital VT/VF arrests from January 2011 to May 2015 experienced by patients wearing a WCD using the manufacturer's postmarket registry. An index shockable sudden cardiac arrest event was defined as the first arrest caused by VT/VF. Event location and clinical outcome were extracted from patient call logs. Survival analysis was performed using the Kaplan-Meier method. A total of 234 in-hospital VT/VF arrests were included (mean age = 65 ± 12 years, male = 74%); 50% had a history of congestive heart failure. The median follow-up time was 6 days (interquartile range 1–4). In the 128 (55%) daytime events (7:00 a.m. to 7:00 p.m.), 24-hour survival was 91%. The 106 (45%) nighttime events (7:01 p.m. to 6:59 a.m.) had 89% 24-hour survival (p = 0.54). Survival outcome by monitored or unmonitored hospital locations were similar. Kaplan-Meir analyses showed no difference in 30-day survival either between weekend and weekday events (72% vs 65%, p = 0.79), or between daytime and nighttime events (64% vs 69%, p = 0.37). In conclusion, WCD use during in-hospital VT/VF arrest correlated with high survival rates regardless of event time or location inside a hospital. Use of a WCD appears to mitigate some of the risks associated with in-hospital VT/VF arrest.