McCarthy's first game in charge will be for the crucial game with fellow strugglers Bolton on Saturday.
The new Black Cats boss told the clubs official club website, www.safc.com: "I’m excited to be joining Sunderland and am up for the challenge ahead.
"In the short term we have nine remaining games this season and, of course, I will be concentrating on lifting the players to get the best possible results in these.
"I’m also excited about the long-term. This is a great club and it deserves success."