Defender George McCartney has rejoined Sunderland on a five-year contract from West Ham for an undisclosed fee, the club have announced on their website.
The left-back returns to the Stadium of Light after two years with the Hammers to become manager Roy Keane's 10th signing of the summer, joining the likes of Djibril Cisse, El-Hadji Diouf, and Northern Ireland team-mate David Healy.
The 27-year-old will also link up with former Hammers team-mate Anton Ferdinand, who moved to Wearside last week.
Manager Keane told the club's official website, www.safc.com: 'It's great to be able to bring George back to Sunderland.
'I've made no secret of the positions I've been looking to strengthen and a left-back was one of my priorities, I'm delighted.
'George's experience will prove invaluable and he shouldn't take long to settle in as he knows a lot of the lads already and obviously he knows the club inside out.
'I'm happy with my squad now. We have strength in depth and healthy competition for places in all areas.
'I'm looking forward to getting on with the season.'
McCartney came through the academy at Sunderland and made his senior debut in a 3-0 League Cup win against Luton in September 2000.
He made 157 appearances for the Black Cats before moving to West Ham two summers ago.
McCartney was an ever-present for the east Londoners last season and he signed a new five-year deal earlier this year.
The club rejected Sunderland's initial approach earlier in the summer but the player handed in a written transfer request.
McCartney, though, revealed on the Hammers website that his return north was for family reasons as his wife had not settled in the capital.
He explained on www.whufc.com: 'I had two great seasons with West Ham and I'd like to thank them for giving me the opportunity to play for a club with the history they have and their fantastic supporters.
'But for personal reasons alone, this move is right for me.'
However, McCartney looked ahead to the challenge at Sunderland, telling the Black Cats website: 'The club has moved on over the last two years and I think there are exciting times ahead.'