In the wake of the COVID-19 pandemic many countries implemented containment measures toreduce disease transmission. Studies using digital data sources show that the mobility of individualswas effectively reduced in multiple countries. However, it remains unclear whether these reductionscaused deeper structural changes in mobility networks, and how such changes may affect dynamicprocesses on the network. Here we use movement data of mobile phone users to show that mobilityin Germany has not only been reduced considerably: Lockdown measures caused substantial and long-lasting structural changes in the mobility network. We find that long-distance travel wasreduced disproportionately strongly. The trimming of long-range network connectivity leads to amore local, clustered network and a moderation of the ‘small-world’ effect. We demonstrate thatthese structural changes have a considerable effect on epidemic spreading processes by ‘flattening’the epidemic curve and delaying the spread to geographically distant regions.