Hugh Ramapolo Masekela was born on April 4, 1939, in Witbank (now Emalahleni), South Africa, the son of Thomas Selema Masekela, a health inspector and sculptor, and Pauline Bowers Masekela, a social worker. He was raised largely by his grandmother, sang and played piano as a child, and at fourteen, after seeing the 1950 film Young Man with a Horn, decided he wanted to play the trumpet. Trevor Huddleston, the anti-apartheid chaplain at St. Peter's Secondary School in Johannesburg, bought him his first instrument and arranged lessons with the leader of the Johannesburg Native Municipal Brass Band, known as Uncle Sauda. Schoolmates soon took up instruments too, and the group became the Huddleston Jazz Band, described as South Africa's first youth orchestra; the trombonist Jonas Gwangwa was in it with him. When Louis Armstrong heard about the band from Huddleston, he sent one of his own trumpets as a gift. By 1956 Masekela had joined Alfred Herbert's African Jazz Revue, and in 1958, after a tour by the Manhattan Brothers, he joined the orchestra of King Kong, Todd Matshikiza's all-African jazz opera, which toured South Africa for a year with Miriam Makeba in the cast.

At the end of 1959 he formed the Jazz Epistles with the pianist Dollar Brand (later Abdullah Ibrahim), the alto saxophonist Kippie Moeketsi, Gwangwa, the bassist Johnny Gertze and the drummer Makaya Ntshoko. The sextet was South Africa's first important bebop band, modeled on Art Blakey's Jazz Messengers; according to Britannica, records by Dizzy Gillespie and Clifford Brown had inspired Masekela's bebop playing. The Jazz Epistles drew record-breaking crowds in Johannesburg and Cape Town and made Jazz Epistle, Verse 1 (Continental), the first LP by a Black South African jazz band. After the Sharpeville massacre of March 21, 1960, and the ban on gatherings of ten or more people, Masekela left the country; Huddleston, Yehudi Menuhin and John Dankworth helped him win a place at the Guildhall School of Music in London. He then reached the United States, where Harry Belafonte befriended him, and studied classical trumpet at the Manhattan School of Music from 1960 to 1964. In New York he heard Miles Davis, John Coltrane and Thelonious Monk, and both Gillespie and Armstrong urged him to develop an African sound of his own.

His first album, Trumpet Africaine (Mercury, August 1962), was recorded in New York with arrangements by Hugo Montenegro while he was still a student. He married Makeba in 1964; they divorced in 1966. Recording for Mercury and then MGM, where Tom Wilson produced, he made the live The Americanization of Ooga Booga (released June 1966), a piano-quartet set with Larry Willis that AllMusic credits with showing off his "township bop" style, and then moved to California, where he started the Chisa label and began working with the producer Stewart Levine. The Emancipation of Hugh Masekela put him on the cover dressed as Abraham Lincoln. He played the Monterey Pop Festival in 1967, had a modest hit with "Up, Up and Away," and in 1968 reached number one on the Billboard Hot 100 with "Grazing in the Grass," an instrumental composed by the actor and singer Philemon Hou and recorded at Gold Star Studios in Hollywood with Levine producing. It sold about four million copies and was inducted into the Grammy Hall of Fame in 2018.

The pop success sat beside more jazz-minded and more political records. Reconstruction (1970) drew on The Crusaders players Wilton Felder, Joe Sample and Wayne Henderson with Al Foster on drums, and Hugh Masekela & The Union of South Africa (1971) paired him with Gwangwa and Caiphus Semenya. In January 1972 he recorded the double album Home Is Where the Music Is at Island Studios in London with the saxophonist Dudu Pukwana, Willis, Eddie Gómez and Ntshoko, which AllMusic calls his finest jazz and African set. After twelve years in exile he travelled through West Africa in 1973, spending time in Kinshasa, Liberia, Ghana and Nigeria; in Lagos Fela Kuti introduced him to the Ghanaian band Hedzoleh Soundz, with whom he recorded Introducing Hedzoleh Soundz in July 1973. With Levine he conceived the Zaire 74 festival in Kinshasa, held September 22 to 24, 1974, around the Ali and Foreman fight. After albums for Casablanca, among them You Told Your Mama Not to Worry (recorded in Ghana, with Makeba singing and including "Soweto Blues"), he teamed up in 1978 with Herb Alpert for Herb Alpert / Hugh Masekela and the live Main Event Live.

From 1980 to 1984 he worked from Botswana, where a mobile studio let him record Techno-Bush and Waiting for the Rain for Jive; "Don't Go Lose It Baby" reached number two on the dance charts. In 1985 he founded the Botswana International School of Music, whose annual workshop continues as the Botswana Music Camp. He joined Paul Simon's Graceland tour, which began on February 1, 1987, alongside Makeba and Ladysmith Black Mambazo. His own "Bring Him Back Home" of 1987 became an unofficial anthem for the movement to free Nelson Mandela, and his song "Stimela" about migrant mineworkers was a fixture of his concerts. With Mbongeni Ngema he wrote the music and lyrics for Sarafina!, which opened at the Market Theatre in Johannesburg in June 1987 and on Broadway in January 1988, where it was nominated for the Tony Award for best original score.

After Uptownship (1989) he returned to South Africa in 1990, following Mandela's release, and kept recording and touring: Beatin' Aroun De Bush (1992), the live Hope, taped at Blues Alley in Washington, D.C., in 1993, and Almost Like Being in Jazz (2005), a flugelhorn standards date with Willis. He published the autobiography Still Grazing (2004) with D. Michael Cheers, took part in International Jazz Day events in Istanbul in 2013 and at the 2015 global concert at UNESCO in Paris, where he performed "Bring Him Back Home" alongside Marcus Miller and Lee Ritenour, and in 2016 reunited with Abdullah Ibrahim in Johannesburg, the first time the two had played together in more than half a century. His final studio album, No Borders, came out in 2016. Masekela passed away in Johannesburg on January 23, 2018, of prostate cancer, at age 78. His marriages included Makeba and Chris Calloway, daughter of Cab Calloway; his son is the television host Selema Masekela. Honors included the Order of Ikhamanga in gold (2010), three Grammy nominations, and a Google Doodle on April 4, 2019, which would have been his eightieth birthday. Rejoice, a collaboration with the Nigerian drummer Tony Allen, was completed after his death and released in March 2020.

Masekela was widely called the father of South African jazz. He learned bebop from American records and from the Jazz Epistles, a band built on the model of Art Blakey's Messengers, then spent his career folding that vocabulary into South African idioms: township jive, mbaqanga strains, and later West African highlife and Afrobeat. Early on, advice from Louis Armstrong and Dizzy Gillespie pushed him toward his own African idiom rather than imitation of American hard bop. His trumpet and flugelhorn sound is bright and singing, with short, rhythmic phrases and a vocal delivery that is part chant and part storytelling; AllMusic notes that he often simplified his playing to fit pop formats but was capable of outstanding ballad and bebop work, which the live Hope and the standards album Almost Like Being in Jazz bear out. Much of his best-known music, from "Grazing in the Grass" to the Casablanca and Jive Afrika albums, sits at the edge of jazz, pop and African popular music, so his subgenre tags reflect only the jazz and jazz-adjacent styles his records genuinely touch. His anti-apartheid songs "Soweto Blues," "Bring Him Back Home" and "Stimela" made him a symbol of resistance, and he influenced generations of South African and African jazz musicians, partly through the Botswana International School of Music he founded in 1985.