Citing multiple sources, MLB.com said the deal was not final but Wells -- who is owed $42 million for two more years on his current contract -- said goodbye to his Angels' teammates and cleared out his locker during Sunday's exhibition game.
ESPN said the Yankees will assume $13 million of Wells' salary and MLB.com said the Angels will acquire a minor league player in the deal.
Angels General Manager Jerry Dipoto had confirmed the two teams were working on a deal but he said there had been "nothing definitive" to announce.
"It'd be a huge change," Wells said at the Angels' training facility. "I don't think it's ever easy saying goodbye, but at the same time, if this were to happen, it's a good group of guys over there. I'll just get to know a new family."
The Angels acquired Wells in a 2011 trade with Toronto, where he hit .279, won three Gold Gloves and went to the All-Star Game three times from 2002-10.
He hit 25 homers in 2011, but his .218 batting average was the lowest in MLB that season. He followed that with another subpar year in 2012 -- batting .244 with six homers in the first two months of the season before missing two months due to surgery for a thumb injury.
He was having a productive spring for the Angels, batting .361 with four home runs and 11 RBI.