O'Hara has signed a five-year contract after a successful loan spell at Molineux during the second half of last season.
He has become the most expensive midfielder in the club's history, beating the ?2.6million paid for Nenad Milijas to Red Star Belgrade two years ago.
O'Hara said: "It's going to be sad leaving Tottenham. I had a great career there and the fans were always different class with me.
"I'll always support Spurs but it's one of those things. I had to move on.
"The chairman and the manager at Wolves put a lot of faith in me after I had been out for a long time with a back problem.
"I was put straight into the side and to make a permanent move now after a scary end to the season (narrowly avoiding relegation) is brilliant.
"I didn't even ask for a five-year deal. They offered me it. It is fantastic. It shows they wanted me and wanted me to be here for the long haul."
O'Hara's goal on the final day of the campaign against Blackburn helped Wolves to ensure a third season of top flight football.
He said: "I don't think we'll have an end to next season like this season.
"It's going to be our third season in the Premier League and hopefully we can push on and be a force to be reckoned with.
"It is definitely a club that is on the way up."
O'Hara added: "I want to achieve things at the club. I wouldn't have signed here if I didn't think this club was going to be pushing forward.
"I think it is a club on the up. It is going to be down to the club and the team to make things happen.
"But I think, with the squad and manager we've got, this coming season we've got to be looking at mid-table and then pushing on from there."
Wolves owner-chairman Steve Morgan is expecting other new faces to be joining the club before the start of the next campaign.
Reading centre-back Matt Mills, Wolves central defender Roger Johnson and Liverpool left-back Paul Konchesky are amongst McCarthy's potential targets.
Morgan said: "Watch this space. I'm not giving anything away but there will probably be one or two more additions.
"I can't comment on specific players. We only ever do that when players arrive."
Morgan believes the 24-year-old O'Hara fits into the category of players Wolves are looking to attract.
He said: "I actually said to Jamie when he first arrived at the club on loan from Spurs that we wanted to make the deal permanent.
"I was a big fan of Jamie when he played for Portsmouth the year before. I thought he was their most outstanding player.
"He almost kept them up and he was just a player who had got 'Wolves' written all over him.
"He is our type of player. We've got one of the youngest squads in the Premier League and Jamie is in the same age group.
"He has got fire in his belly and he just totally fits in to what we are all about at Wolves and where we are taking the club."
Source: Team Talk
Source: Team Talk