Borini, who spent the 2013-14 season on loan at Sunderland, signed a four-year contract for an undisclosed fee understood to be around £7million ($10.8million, 9.6million euros), with a further £2 million in potential add-ons.

"Sunderland are delighted to announce the signing of Fabio Borini from Liverpool for an undisclosed fee," a statement on the club's website confirmed.

"The 24-year-old has signed a four-year deal at the Stadium of Light and returns to the club following a successful loan spell during the 2013-14 season, during which he became a fan favourite with 10 goals including strikes against Newcastle United, Chelsea and at Wembley during the League Cup final."

The Black Cats' former head coach Gus Poyet had wanted to sign Borini on a full-time contract last year, but was unable to persuade him to turn his back on his ambitions at Anfield.

However, Borini was unable to force his way into Brendan Rodgers' plans, making just 18 Liverpool appearances last season.

There had been speculation that Watford could tempt Borini to Vicarage Road, but Sunderland, who collected their second league point of a testing start to the new season in a 2-2 draw at Aston Villa on Saturday, beat them to the punch with a lucrative deal.

The signing is a boost to Sunderland manager Dick Advocaat, who has spent much of the last few weeks bemoaning the lack of quality in his squad and urging owner Ellis Short and sporting director Lee Congerton to resolve that issue.

"Fabio is a great addition to the squad who will make our front line stronger. He can play in a number of attacking positions which is a huge benefit to the team," Advocaat said.

Borini joins Jeremain Lens, Yann M'Vila and loan signing Ola Toivonen on the list of Sunderland's recent signings, and Advocaat will hope he can make a similar impact to his previous spell on Wearside as the Black Cats try to avoid a relegation battle.