Golson helped the Irish go 12-0 during the regular season last year, regain the No. 1 ranking for the first time in nearly two decades and get to the national title game against Alabama in January. Coach Brian Kelly was counting on him to play an even bigger role in 2013 after his play steadily improved throughout last season.
Golson did not specify what he did to get suspended, and wrote that he understands his integrity could be in question.
"But I want to reassure my supporters that through this experience I will return a better student athlete as well as a better individual," he said.
He said he chose to attend Notre Dame because of its mission to develop him both on and off the field.
"My parents and the community I grew up in have instilled values in me that have and will continue to allow me to be successful in the future. There have been many lessons learned as I worked to become the starting quarterback at Notre Dame and each was a result of Coach Kelly's belief in me as an athlete and a person," he wrote.
Athletic Director Jack Swarbrick declined to elaborate on Golson's situation earlier in the day. Brown said the university would have nothing to add to Golson's statement.
Golson's abrupt exit leaves the Irish unsettled at a position they were hoping would be a strength in 2013. The most likely replacement is Tommy Rees, the 2011 starter who played key roles in four victories last season when Golson either struggled or was injured.
Golson completed 58.8 percent of his passes last year for 2,405 yards with 12 touchdown passes and six interceptions. He also ran for 298 yards and team-high six touchdowns.
Notre Dame also has Andrew Hendrix, a senior with no starts, and freshman Malik Zaire at quarterback.