It was announced last November that South Africa's Test skipper Smith would take the lead at Surrey from the 2013 campaign onwards, and the 32-year-old has revealed he would rather have a long-term contract in place than circulate on shorter deals like he has in recent years with the likes of Indian Premier League outfit Rajasthan Royals.
"It is a three-year deal and I think that shows how important it is to me and my career and how much I want to make a success of it," Smith said.
"I feel that I have had a few years of the IPL and, for me personally, I was looking forward to a new challenge. At this stage of my career I didn't want to have a fast-fix situation, a short-term option. I want the opportunity to come in and establish myself."
Smith will lead Surrey into their first competitive match of the season on April 17 when they take on Somerset, the club with which Smith has his only other taste of first-team county cricket after a spell at the County Ground in 2005.
The South African, who also had a spell with Hampshire as a teenager, is looking forward to playing alongside his new team-mates and ultimately wants to bring success to The Oval.
"It is a proud day for me to represent such an important club, a club with such stature. But mostly to represent the players, they are a hugely talented bunch of cricketers and I'm very, very excited," he added.
"The option came up through [former England captain] Alec Stewart to join Surrey. I gave it some thought and after the tour [South Africa's tour of England last summer] I felt it was a challenge I was looking forward to - to hopefully create something with the group of players that we can all be proud of."
Surrey team director Chris Adams believes the club have secured the services of a true great and admits everyone involved with the county is looking forward to teaming up with Smith.
"I think it is fair to say that Graeme Smith is the leading captain of his generation and era and possibly one of the greatest the world has ever seen," he said. "We very much look forward to seeing him out there next week doing what he does best - scoring runs and leading the team to what we hope will be success."