Ellen DeGeneres is winning the top US humour prize 15 years after breaking ground as the first lead character on primetime TV to reveal she's gay.

The Kennedy Centre in Washington has announced that the talkshow host will receive the 15th annual Mark Twain Prize for American Humour.

Ellen will be honoured on October 22 with a line-up of celebrity performers.

In a statement, the star said receiving the same award as Bill Cosby, Tina Fey and Will Ferrell makes her wonder, "why didn't I get this sooner?"

In 1997, Ellen came out on Time magazine's cover and on TV's Ellen to a record 46 million viewers. The sitcom was cancelled a year later.

She later bounced back with movie roles and a hit talk show.