Williams was born in Christchurch to Gary and Roseanne Williams, and moved to Nelson when he was twelve months old. His younger brother is comedian Paul Williams. He attended primary school at St Joseph's School, and was educated at Nelson College from 2001 to 2005; in 2005 he travelled to Gallipoli with Prime Minister Helen Clark after winning a student essay competition. He was a member of the school's 'A' basketball team from 2003 to 2005.Nelson College Old Boys' Register, 1856–2006, 6th edition
