The 29-year-old penned a three-year deal at the Stadium of Light after his contract with Wigan Athletic expired at the end of June.
Poyet feels that the Spaniard has all the attributes needed to be a success in his team.
He told the club's official website: "Jordi Gomez is a special player because he's a 'number 10', which not too many can play in England, but because he's been here for a while he knows what is needed.
"He's going to bring technical quality and ability in the last third, with the understanding of the power, fitness and physicality of English football.
"He understands the way we want to play and he's going to bring plenty of quality."