Wilson pitched collegiately at Louisiana State University. His college career ended during his junior season, when he injured his elbow and underwent Tommy John surgery. The San Francisco Giants selected him in the 2003 draft. He reached the major leagues in 2006 and had become the Giants' regular closer by the end of 2007. In 2010, he led the Majors with 48 saves which tied the franchise single season record while posting a 1.81 ERA, and he saved clinching games at every level of the playoffs, including the 2010 World Series over the Texas Rangers.