Non-pharmaceutical interventions have been implemented worldwide to curb the spread of the COVID-19 pandemic. Despite recent reductions of new infections and deaths in Europe, the effectiveness of such governmental measures is still unclear. In this article, we estimate the effects of reduced mobility on excess mortality at the regional level in England and Wales using digital mobility data provided by Google. We find no immediate effect of mobility restrictions on mortality. A robust relationship between more time spent at home and lower excess mortality emerges after accounting for a five-week lag between the two measures. We estimate that, in the absence of observed mobility reductions, the number of excess deaths could have been more than doubled. Our results have important policy implications for future pandemics and a potential second wave of COVID-19.