The Crawley-born 23 year-old, who is a product of the Sussex youth and academy set-up, played 14 first-class matches during the 2012 season, scoring more than 500 runs, as well as taking 38 catches behind the stumps.
He also featured in 10 Clydesdale Bank 40 matches and five Friends Life t20 games.
The former England under-19 player has recently been representing England in the Hong Kong Sixes tournament with Sussex team-mate Chris Nash.
Brown said: “I’m really privileged to have signed for my home county for the next two years.
“I’m determined to be a major part of the club’s future and I’m also hopeful that I can help us to win trophies across the next couple of seasons.”
Sussex captain Ed Joyce said: “Ben has become an integral member of the side over the last couple of seasons.
“He’s a hugely talented and hard-working cricketer and the improvements he made to his all-round game this year reflect that. He was also a huge help to me tactically on the field since I took over the captaincy.”