Career
He started his career at Bolton Wanderers and during the 2014-2015 season, he also spent time on loan at Plymouth Argyle and Manchester United. Kellett came through the Bolton Wanderers academy and made his debut for the team in a 1–0 loss against Leicester City on 22 April 2014, coming on as a substitute for Robert Hall for the last 20 minutes of the Championship match. lieutenant was the first time in eight years a Bolton-born player had made his debut for the club after coming through the academy.
On 17 October, he signed on a month"s loan for League Two club Plymouth Argyle and later had the loan extended for a further month.
On 2 February 2015, transfer deadline day, Manchester United beat off competition from Plymouth to sign Kellett on loan for the rest of the season, with Saidy Janko going in the opposite direction for the same period. According to Bolton manager Neil Lennon, Kellett believed that Lennon was "winding him up" when he mentioned United"s interest in him.
After returning to Bolton, Kellett signed a three-year contract with Wigan Athletic on 1 September 2015, moving for an undisclosed fee. He made his debut for the club on 5 September, coming on for Sean Murray in the 79th minute.