During his seven-decade career, Harry Belafonte has been a singer, an actor, a friend to Martin Luther King Jr., a Unicef good-will ambassador, an anti-apartheid activist and more. “I’m at a time of life when I’m examining the entire journey,” he said one recent afternoon at his Manhattan home, lamenting how the dreams of the civil rights movement are far from realized. “When I was 20 and 30, my visions for what the world would be, all things were possible.”

Mr. Belafonte, for whom art and activism have been inextricably linked, said his life is a “call and response,” and, at 89, he isn’t ready to retire from being one of society’s most passionate and visible advocates just yet.

This weekend, “Many Rivers to Cross,” a two-day “music, art and justice” festival in the Atlanta area focuses on three issues: voting, mass incarceration, and the relationship between community and law enforcement.

The lineup features an array of genres and musical styles: John Legend; Carlos Santana; Goapele; Dave Matthews; and Tip Harris, better known as the rapper T.I., are scheduled to take to the stage, alongside Chris Rock, the poet Sonia Sanchez, the actor Jesse Williams and the activist Umi Selah of the Dream Defenders. The event will raise money for Sankofa.org, a social justice organization founded by Mr. Belafonte that unites grass-roots organizations and artists in the fight against problems like income disparity and inequities in the justice system.

“What makes a movement work are thousands of parts that come together and express itself in favor of a given destination or objective,” he said. “You have to find men and women who are willing to play the role that each of these things demand.”

With Election Day nearing in what has been a contentious presidential race exposing deep ideological divides, registration services will be available to help attendees ahead of nationwide deadlines.

“The vote is perhaps the single most important weapon in our arsenal,” Mr. Belafonte said. An area called the social justice village will feature representatives from over 40 organizations. The goal is to allow festivalgoers to “walk away with tools to better go out and support the causes they care about,” said Gina Belafonte, who helped organize the event with her father.

Mr. Belafonte said, “When Trayvon Martin was shot and our community went into a response to that, there was no question in my mind that America was being awakened to its reality.” Thinking back to the 1950s and ’60s, when he toiled alongside activists including Dr. King, Julian Bond and Fannie Lou Hamer, Mr. Belafonte recalled how Dr. King represented a “harvest of opportunity.” He added: “The energy that went into the movement disappeared because people were reaping the benefits. We’ve forgotten what the opportunity was about.”

In 2012, a brouhaha ensued after Mr. Belafonte asserted that today’s celebrities have “turned their back on social responsibility” and mentioned Jay Z and Beyoncé. Jay Z responded in an interview with Rap Radar’s Elliott Wilson by saying among other things, “my presence is charity.” Mr. Belafonte said that he extended an olive branch and that he and Jay Z met one on one. But Mr. Belafonte fervently maintains that artists must do more to champion causes.

“There’s no evidence that artists are of the same passion and of the same kind of commitment of the artists of my time,” he said. “The absence of black artists is felt very strongly because the most visible oppression is in the black community.”

Mr. Belafonte provides counsel to celebrities and organizations, saying that he draws parallels between the roadblocks and successes of the ’50s and ’60s and those of the present political movements.

Linda Sarsour, the executive director of the Arab American Association of New York, said conversations with Mr. Belafonte had proved critical. “Mr. B plays no games with us,” she said. “When he doesn’t think we’re doing the right thing, he tells us. He said, ‘Look, you need the wisdom of your elders, but we need your energy right now.’”

T.I., who will perform at “Many Rivers to Cross” on Saturday, said he felt compelled to take action; his latest EP, “Us or Else,” addresses interactions between law enforcement and blacks, among other issues, and part of its proceeds benefit Sankofa.org.

It just seemed all too consistent, all too repeated, all too ignored,” he said of police killings of black people. In the widely viewed video for the song “Warzone,” which he will perform at the festival, he spotlights the cases of Eric Garner, Tamir Rice and Philando Castile. “It was very insightful to hear from someone who had been through so much and been a part of history in so many ways,” he said of his meeting with Mr. Belafonte.

With his 90th birthday on his mind, Mr. Belafonte paused to take stock. “I wake up at the age of 90, and I look around and say, ‘What do we need now?’” he said.

“Well, the same things needed now are the same things needed before,” he went on. “Movements don’t die because struggle doesn’t die.”