In October 2013, Williams was appointed Parliamentary Under Secretary at Department for Communities and Local Government (DCLG). As communities minister, his responsibilities included community cohesion, race relations, localism and community rights, empty homes, housing standards, building regulations, neighbourhood planning, climate change and sustainable development. In March 2014, Williams published the Government's proposals following the housing standards review, which recommended a rationalisation of government, local authority and industry housing standards into a national set. As Minister for Communities, Williams also announced new funding for promotion of the Cornish language and gave recognition to the people of Cornwall as a national minority on the same basis as the other celtic people of the British Isles. In 2017, it emerged that Williams had responded to 2014 concerns from the All-Party Parliamentary Fire Safety and Rescue Group about the fire safety of Britain's tower blocks, especially the absence of sprinklers in many of these, by saying, "I have neither seen nor heard anything that would suggest that consideration of these specific potential changes is urgent and I am not willing to disrupt the work of this department by asking that these matters are brought forward." The correspondence was leaked to the BBC after the Grenfell Tower fire.