Household food security, which may be compromised by short-term income shocks, is a key determinant of health. Since 2012, the UK witnessed marked increases in the rate of ‘sanctions’ applied to unemployment insurance claimants, which stop payments to claimants for a minimum of four weeks. In 2013, over 1 million sanctions were applied, potentially leaving people facing economic hardship and driving them to use food banks. Here we test this hypothesis by linking data from the Trussell Trust Foodbank Network with records on sanctioning rates across 259 local authorities in the UK. After accounting for local authority differences and time trends, as the rate of sanctioning increased by 10 per 100,000 adults, the rate of adults fed by foodbanks by an additional 3.36 adults per 100,000 (95% CI: 1.71 to 5.01). The availability of food distribution sites affected how tightly sanctioning and food bank usage were associated (p<0.001 for interaction term), such that in areas with few distribution sites, rising sanctions led to smaller increases in Trussell Trust food bank usage. Sanctioning appears to be closely linked with rising need for emergency food assistance, but the impact of sanctioning on food insecurity is likely not fully reflected in available data. There is a need to monitor household food insecurity in the UK to fully understand the impact of government policies on this outcome.