The 22 year-old left the Oval for a reported £50,000 fee back in 2015 but just two years on, has been released by the League One club.
Stewart’s spell at the County Ground was hampered by a knee injury that saw him undergo surgery in November.
At the end of a tough first season at the club, Stewart had been loaned out to National League side Grimsby Town.
After getting a pre-season under his belt, Stewart had been hoping to kick-start his professional career this term but, partly thanks to injury, the pacy winger didn’t start a single league game for Swindon.
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Stewart burst onto the scene at Glentoran in 2013 aged just 18 and netted 23 goals in 67 appearances, earning his move to England.