A Northern Ireland U17 international, Grainger was born in England and progressed through the academy ranks at Leeds before joining Forest in 2025, where he was involved in their U21 squad in Premier League 2.
The 19-year-old was part of a strong Northern Irish contingent at the City Ground with Kalum Thompson, Matthew Orr and Blaine McClure at the club, while Mason Ayre joined Forest’s academy this summer from Glentoran.
Portstewart have made an impressive start to the new National Conference League Premier Division under manager David McDaid, winning their opening two matches against Ballymacash Rangers (3-0) and Oxford Sunnyside (4-1).
Gregg Shannon (left) welcomes Owen Grainger to Portstewart. (Photo by Portstewart FC)placeholder image
Gregg Shannon (left) welcomes Owen Grainger to Portstewart. (Photo by Portstewart FC)
McDaid’s men also secured progression past Ballymacash in the National Conference League Cup earlier this month.
Former Larne striker McDaid has signed the likes of ex-Premiership stars Caolan Loughran and Alex Gawne this summer and Shannon believes the arrival of Grainger represents another statement.
“Owen is a fantastic goalkeeper and comes to us with an impressive background and an abundance of experience with the levels he’s played at and the coaches he’s worked under,” Shannon told the club’s social media. “A genuinely huge addition to our team.
"Owen choosing Portstewart to further his career goes to show the direction the club is headed.”
Grainger played three times for Northern Ireland’s U17s during their European Championships qualifying campaign in 2023 and 2024, starting against San Marino, France and Hungary.
He was also called up by Northern Ireland’s U18s for friendlies against England and Morocco in May 2024.