A youth-team graduate with Middlesbrough, Jason made his professional debut on loan at Northampton Town in February 2010 against Cheltenham Town.
He made his Boro bow against Chesterfield in the League Cup that August and went on to appear over 140 times for the club.
A member of the GB Olympic squad in 2012, he was a regular on Teesside for three seasons before joining fellow Championship side Blackburn Rovers in September 2014, initially on loan.
He joined permanently three months later and was a regular for three years before a return to the north east with Sunderland, ahead of the 2017/18 season.
Making 15 Championship appearances for the Black Cats, he moved to Brighton & Hove Albion in the summer of 2018 and put in a man-of-the-match display on his debut against AFC Bournemouth in the third round of the FA Cup the following January.