Bennett, who marched with the civil rights leader in Selma, Ala., in 1965, is scheduled to perform as part of Saturday's festivities commemorating the historic march and King's "I Have A Dream" speech at the Lincoln Memorial.
The entertainer said Thursday he wants to honor King's humanitarian message, but will also be in Washington as part of the Voices Against Violence campaign that is pushing for gun limits.
The Rev. Al Sharpton is holding an event on Saturday with King's son, Martin Luther King III. And President Barack Obama will speak on the actual anniversary day Wednesday.