In 1964, Makeba released her second studio album for RCA Victor, The World of Miriam Makeba. An early example of world music, the album peaked at number eighty-six on the Billboard 200. Makeba's music had a cross-racial appeal in the US; white Americans were attracted to her image as an "exotic" African performer, and black Americans related their own experiences of racial segregation to Makeba's struggle against apartheid. Makeba found company among other African exiles and émigrés in New York, including Hugh Masekela, to whom she was married from 1963 to 1968. During their marriage, Makeba and Masekela were neighbours of the jazz musician Dizzy Gillespie in Englewood, New Jersey; they spent much of their time in Harlem. She also came to know actors Marlon Brando and Lauren Bacall, and musicians Louis Armstrong and Ray Charles. Fellow singer-activist Nina Simone became friendly with Makeba, as did actor Cicely Tyson; Makeba and Simone performed together at Carnegie Hall. Makeba was among black entertainers, activists, and intellectuals in New York at the time who believed that the civil rights movement and popular culture could reinforce each other, creating "a sense of intertwined political and cultural vibrancy"; other examples included Maya Angelou and Sidney Poitier. She later described her difficulty living with racial segregation, saying "There wasn't much difference in America; it was a country that had abolished slavery but there was apartheid in its own way."
Soon after her testimony, Haile Selassie, the emperor of Ethiopia, invited her to sing at the inauguration of the Organisation of African Unity, the only performer to be invited. As the fact of her ban from South Africa became well known she became a cause célébre for Western liberals, and her presence in the civil rights movement provided a link between that movement and the anti-apartheid struggle. In 1964 she was taught the song "Malaika" by a Kenyan student while backstage at a performance in San Francisco; the song later became a staple of her performances.
Throughout the 1960s, Makeba strengthened her involvement with a range of black-centred political movements, including the civil rights, anti-apartheid, Black Consciousness, and Black Power movements. She briefly met the Trinidadian-American activist Stokely Carmichael—the leader of the Student Nonviolent Coordinating Committee and a prominent figure in the Black Panther Party—after Belafonte invited him to one of Makeba's concerts; they met again in Conakry six years later. They entered a relationship, initially kept secret from all but their closest friends and family. Makeba participated in fundraising activities for various civil rights groups, including a benefit concert for the 1962 Southern Christian Leadership Conference that civil rights activist Martin Luther King Jr. referred to as the "event of the year". Following a concert and rally in Atlanta in support of King, Makeba and others were denied entrance to a restaurant as a result of Jim Crow laws, leading to a televised protest in front of the establishment. She also criticised King's Southern Christian Leadership Conference for its investment in South African companies, informing press that "Now my friend of long standing supports the country's persecution of my people and I must find a new idol". Her identity as an African woman in the civil rights movement helped create "an emerging liberal consensus" that extreme racial discrimination, whether domestically or internationally, was harmful. In 1964 she testified at the UN for a second time, quoting a song by Vanessa Redgrave in calling for quick action against the South African government.