Washington exited the series in 2007 after an on-set clash the year before, in which an anti-gay epithet was directed at another cast member at the time, T.R. Knight.
Washington's return as Dr. Preston Burke coincides with the announced departure of series star Sandra Oh at the season's end in May. Her character, Dr. Cristina Yang, was engaged to Washington's Burke at one point in the long-running drama.
The date of Washington's episode was not announced.
During the controversy involving him, Washington also used the epithet backstage at the 2007 Golden Globe awards. He publicly apologized and tried to make amends by meeting with gay-rights organizations.