DeGeneres, host of the popular daytime talk show The Ellen DeGeneres Show, will use her high profile to raise awareness of the disease and give hope to AIDS sufferers, Clinton said in announcing the appointment.

"The enormous platform of your television show and your social media channels will enable you to reach millions of people with the strong and hopeful message that we can win this fight," Clinton said in a statement.

Besides her Emmy-award winning television show, DeGeneres boasts an estimated 8 million Twitter followers and nearly 6 million Facebook fans.

DeGeneres said she was honored by the appointment.

"The fight against AIDS is something that has always been close to my heart. And I'm happy that I can use my platform to educate people and spread hope," she said.

In one of her trademark self-deprecating quips, she added: "Now, if you'll excuse me, I have to go look up what 'envoy' means."

One of the first nationally known celebrities to come out as a lesbian, when she was still starring on her network sitcom, DeGeneres has worked on behalf of many humanitarian causes including anti-bullying, animal rescue and rehabilitation and breast cancer awareness.

"An AIDS-free generation would be one of the greatest gifts we could give to our collective future," DeGeneres said on Twitter.

- Reuters