The 26-year-old joined the Black Cats for on loan until the end of the season from Estudiantes after a successful spell at the Stadium of Light last season.
"I feel very comfortable here at Sunderland," Vergini told the club's official website. "The organisation of the club and the Premier League means that the player has absolutely no concerns.
"In terms of the way that we have started the season it looks like we haven't been very consistent, but the hope is that in the coming games this will change."
Vergini has played in two of Sunderland's three matches at the start of the 2014-15 campaign.