The campaign was not immediately asking for donations but simply raising awareness and recruiting new advocates, Bono said Wednesday at an event announcing the public service announcements
"We're not just asking for people to put cash in the pot here," Bono said. "Americans are generous, we know they'll do that. We're not actually asking for their money, we're asking for their voice."
Pitt, who visited Africa after being inspired by Bono's advocacy, said he was struck by how extreme poverty there has made it difficult for the sick to gain access to drugs to minimize the effects of AIDS.
"I've seen it, I've been there, and to walk away from it and turn my back makes me culpable," Pitt said. "And I can't do that."
"Do we really believe in our hearts that we're all equal? And if we believe this, what are we going to do about it?" he said.
Pitt said he believed deeply in Bono's effort, titled "ONE: The Campaign to Make Poverty History." (search)
"We can do this. We can do this," he said of eliminating poverty. "It's ambitious, but we can do it."
Pitt, who stars with Angelina Jolie in the upcoming "Mr. & Mrs. Smith," said he was returning to Africa in several weeks but was unsure what else he would do for the campaign.
"This is just a beginning for me," he said.
Bono, who has been nominated for this year's Nobel Peace Prize, said it was "wholly unacceptable" for children to die for lack of cheap immunizations.
"I'm going to spend the rest of my life on this, I'm going to make that kind of extreme poverty history," Bono told reporters.
"I'm in," Pitt responded.
Bono and Pitt were joined by Jack Valenti, the former top lobbyist for the film industry, and actor Djimon Hounsou, a native of Benin.
A 60-second ad to air Sunday night on various networks and cable channels features actors, musicians and religious leaders. Among them are Jewel, Penelope Cruz, Tom Hanks and Mos Def.
Also featured are Al Pacino, Jamie Foxx, and Hounsou as well as evangelist Pat Robertson and the Rev. Frank Griswold, presiding bishop of the Episcopal Church in the United States.
Completing each other's sentences, each appear in black-and-white, peering into the camera and saying a few words.