Stewart missed much of the 2025-26 campaign with a hamstring issue but remained effective when fit, recording nine goals and two assists across 27 league matches.
He also netted twice during Southampton’s run to the FA Cup semi-finals, opening the scoring in their quarter-final triumph over Arsenal.
As a youngster, Stewart featured for Ardeer Thistle and Kilwinning Rangers before signing for Albion Rovers in 2016.
The Irvine-born forward then turned out for St Mirren, Alloa Athletic and Ross County—where he captured the 2018-19 Scottish Championship and Scottish Challenge Cup—prior to joining Sunderland in 2021.
He was prolific with the Black Cats, scoring 40 goals in 81 games, helping them win the EFL Trophy in 2021 and secure promotion to the Championship the following season.
His displays at the Stadium of Light earned a move to Southampton in 2023, where he totaled 12 goals in 50 appearances.
“We’re thrilled to bring Ross to Swansea City; he offers a great deal of experience on and off the pitch,” said the club’s sporting director, Ben Stevens.
“His standout Championship performances last season rightly earned him a place in Scotland’s World Cup squad. We can’t wait to see Ross in a Swansea shirt.”
Stewart is Swansea’s sixth permanent signing of the summer, following Moussa Yeo, Elijah Just, Joseph Opoku, Stephen Welsh and Leo Walta, who was on loan last season.
They have also brought in Benfica left-back Tiago Parente on loan.
Valencia’s Andre Almeida and Randers midfielder Ousseynou Fall Seck remain on the Swans’ shortlist of targets.