DeGeneres tweeted, "It's official: I'm hosting the #Oscars! I'd like to thank @TheAcademy, my wife Portia and, oh dear, there goes the orchestra."
The Oscars will be held on March 2 at the Dolby Theatre in Hollywood and will again be produced by Craig Zadan and Neil Meron.
"We are thrilled to have Ellen DeGeneres host the Oscars," Zadan and Meron said in a statement. "There are few stars today who have Ellen's gift for comedy, with her great warmth and humanity. She is beloved everywhere and we expect that the audience at the Dolby Theatre, and in homes around the globe, will be as excited by this news as we are."
The 55-year-old DeGeneres has been hosting "The Ellen DeGeneres Show" since 2003, earning 45 daytime Emmys during 10 seasons. She has hosted the Oscars once before in 2007 and received an Emmy nomination for outstanding individual performance in a variety or music program.
"I am so excited to be hosting the Oscars for the second time. You know what they say - the third time's the charm," DeGeneres said in a statement.
Last year's Oscar show featured "Family Guy" creator Seth MacFarlane as host, drawing 40.3 million viewers - Oscar's largest audience since 2010, including more coveted younger viewers.