 Miller signed a 16-month contract with Conference National club Grimsby Town and made his debut in the starting eleven as the "Mariners" beat Lincoln City 3–1 on 1 January 2012.On 17 February 2012 he scored the equaliser in the 1–2 away victory at Southport, which was also his first goal for Grimsby, a corner from Frankie Artus was met with a powerful header by Miller inside the six-yard box.Miller was ever present for Grimsby during the 2012–13 season and played in the FA Trophy final at Wembley Stadium which ended in a defeat on penalties to Wrexham.