London - Sunderland confirmed the appointment of Martin O'Neill as manager of the struggling English Premiership club on a three-year contract on Saturday.
O'Neill, 59, replaces Steve Bruce, who was sacked earlier this week, and is back in management after a year out of work following his exit from Aston Villa.
"It's a very nice feeling to be back in football and to be the manager of Sunderland. It's a big moment for me," O'Neill told Sunderland's website.
The former Celtic and Leicester boss will officially take charge from Monday, but he is expected to be in the stands on Sunday when Sunderland face relegation rivals Wolves at Molineux.
Sunderland have won just twice in 13 league games this season and are currently only two places and two points above the relegation zone.
But O'Neill led Villa to three successive sixth place finishes in the league and he is hopeful of replicating that impressive achievement at Sunderland.
"I'd heard about what a good club it was but coming here, seeing the stadium and the training ground, I've been bowled over. It's absolutely fantastic," O'Neill said.
"I hope I can help Sunderland to a very successful period. That's what I've come for and that's my driving ambition."
Sunderland have moved swiftly to get their man following Bruce's departure on Wednesday in the wake of a 2-1 home defeat by his former club Wigan which proved the final straw for chairman and owner Ellis Short.
They have won just three games at home in 2011, a return which severely hampered Bruce's hopes of establishing the club in the top half of the league.
O'Neill was undoubtedly the fans' favourite from the moment Bruce was relieved of his duties, and his name has been on the lips of supporters for several years as a result of his boyhood affection for the club.
One of O'Neill's first tasks will be to assess the squad he has inherited from Bruce and decide where it may need strengthening.
His predecessor presided over a major summer reshuffle which saw 11 new faces arrive, but there are significant deficiencies, particularly in attack where Bruce never really managed to replace Darren Bent, Asamoah Gyan and Danny Welbeck.
Short believes his short time in O'Neill's company while they negotiated his appointment showed he was the right man for the job.
"Having spoken with Martin over the last two days I know he is brimming with enthusiasm and anticipation about the challenge of taking Sunderland forward and I believe he is the perfect choice to deliver the success we all desire," Short said.
"Martin has as good a managerial pedigree as you could wish to find and has proven over the years to be a very astute, top-level manager.
"During his time at Aston Villa he established the club firmly in the top 10 of the Premier League year-on-year and this is something we are striving to achieve at Sunderland."