A club statement read:
Sunderland AFC has today announced the appointment of Gustavo Poyet as head coach.
The 45 year-old has agreed a two-year contract at the Stadium of Light and will take charge of the Black Cats with immediate effect.
According to the club website, Poyet will be joined at the Stadium of Light by his backroom staff Mauricio Taricco and Charlie Oatway.
The news had been expected on Monday evening, when John Percy of the Daily Telegraph reported via Twitter that Poyet would be unveiled imminently:
Sunderland chairman Ellis Short briefly commented on the appointment in Tuesday's statement, saying: “We analysed a wide range of candidates and believe that Gus's track record, experience, commitment and passion make him the right man to take us forward."
Poyet, 45, left Brighton in unusual circumstances, having appeared to be sacked live on television during the Confederations Cup. However, with the departure of Paolo Di Canio from Sunderland after just five games this season, he makes a swift return to club management.
It will be a far from easy task for Poyet to take on, however, with Sunderland bottom of the table having earned just one point from their opening seven games of the campaign.
Difficult games against Swansea (away) and neighbours Newcastle (home) follow the international break, so Poyet will have to immediately find his stride to avoid the club's situation worsening further.
Poyet will be expected to come in and hastily unify the dressing room and coach the Black Cats to Premier League survival following a summer in which they made an incredible 14 new signings, offloading several senior players.
At Brighton, the former Chelsea and Tottenham midfielder oversaw the club's rise from League One to the Championship playoff semifinals over the course of three seasons.
However, within days of Brighton's playoff defeat last term, Poyet was suspended by the club and was relieved of his position on June 23, when the Seagulls published a statement announcing his sacking.
Over the past two weeks, Poyet had been quick to declare his interest in the Sunderland job and pushed his credentials in the media. Per ESPNFC's Kristan Heneage, he told South American radio station Sport 890:
It's a new team, very international, and it would be convenient for the new person to speak various languages. You wouldn't need to have translators continually.
That is something that helps me, because I have that ability. But there are things that go against me, for example the fact that I've never managed in the Premier League.
Since Di Canio's sacking, Poyet had been among the leading candidates for the position and emerged as the firm favourite in recent days.
In his relatively short managerial career he has shown an ability to galvanise a squad and introduce tactically intelligent football, while signings such as Vicente at Brighton display his knowledge of the foreign market.
Always a bullish character, even as a player, his personality will help lift the gloomy mood currently at Sunderland, which is crucial when fighting a relegation battle.