Gildart was born in Hindley, Greater Manchester, England to parents Claire and Ian, a former professional rugby league footballer for Wigan, Wakefield, and Oldham. He is of Italian descent through his mother, and is eligible to represent the Italian national team.
Club career
2015
A product of Wigan's junior system, Gildart made his Super League début on loan for SalfordRed Devils in 2015, making a total of three appearances before returning to his parent club. He made his début for Wigan in the Super 8s match against Warrington Wolves on 21 August 2015, scoring a try. He then kept his place in the Wigan team for the remainder of the 2015 season, including an appearance in the 2015 Super League Grand Final at Old Trafford in only his tenth career match.
2016
Gildart continued to show promise throughout the course of the 2016 season. One of the signature tries of the year was scored by him in an away match in Perpignan as he straightened up the line and seared his way to the try-line after a flowing length-of-the-field attack by Wigan. He became a fixture in the centres for Wigan. Gildart scored a try in the 2016 Super League Grand Final against the Warrington Wolves which brought Wigan level at 6–6 before they'd go on to win 12–6 at Old Trafford.
2017
He was also part of the Wigan team who defeated NRL champions, the Cronulla-Sutherland Sharks 22–6 to win the World Club Challenge, which ensured Oliver would join father Ian as a World Club Challenge medal winner. Oliver also scored a try in that game. After starting the season is great form he broke three vertebrae in his back following a Brett Ferres 'crusher' tackle. Gildart was ruled out for three months. He returned with a try against the Leigh Centurions on 8 June. He scored a few weeks later against the Warrington Wolves followed by a brace against Leeds. In the Challenge Cup semi-final against Salford he scored another brace and went on to score another try in the 2017 Challenge Cup Final defeat by Hull F.C. at Wembley Stadium. Against tradition rivals St. Helens he scored the opening try followed by a slick move within the first two minutes. Just a few moments later following a Ben Barba mistake his raced 40 yards to complete his brace.
2018
He played in the 2018 Super League Grand Final victory over the Warrington Wolves at Old Trafford.
