He believes the club has made great strides since he left to join West Ham two years ago.

The 27-year-old last night agreed to rejoin the Black Cats on a five-year contract from the Hammers for an undisclosed fee.

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.

He will link up with former Hammers team-mate Anton Ferdinand, who moved to Wearside last week.

McCartney told the club's official website, www.safc.com: "It's a great move for me and great to be back at Sunderland.

"The club has moved on over the last two years and I think there are exciting times ahead.

"The fans were always good to me and I hope that will continue and that we can have a good season.

"The club has changed a lot since I left, but there are still a few familiar faces around. I can't wait to get going."

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 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 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."

Keane said of McCartney's return: "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's capture concluded a busy day for Sunderland, with defender Danny Higginbotham returning to Stoke after only one season on Wearside.