Many improvements are planned at the old ballpark, they said.
"It is an honor to have the opportunity to protect and preserve Fenway Park," said principal owner John W. Henry.
"We see how its history and charm attract people from all over the world, and how it helps connect generations within families."
Fenway has undergone a number of changes in recent years.
Improvements under way, or in the planning stages, include a new playing field with modern drainage, a major expansion of the clubhouse and the establishment of a year-round restaurant.
Fenway Park, the oldest ballpark in the big leagues, opened in 1912.
"We will now begin to plan the Fenway Park Centennial, in 2012, sure to be a great celebration and a historic achievement," CEO Larry Lucchino said.