Should Berra successfully complete a medical at The Molineux over the weekend then he will be unveiled as a Wolves player on Monday.
"We've agreed a fee and if he passes a medical, which I've no doubt he will, then he'll be signed," McCarthy told the official Wolves website.
"I'm delighted because Christophe will be a really good addition to the squad.
"He's 6ft 3in, left footed with a bit of pace and a good defender who reads the ball well and is good in the air.
"He was the captain of Hearts and is an ambitious lad who's in the Scotland squad at the moment and will be driven in wanting to get to the Premier League.
"We tried to sign Christophe last summer and we seem to have done it now which I'm delighted with."