Bernard Atwell McKinney was born in Detroit on November 26, 1932, into one of the city's most concentrated musical families. His father, Clarence Howard McKinney, taught music in the Detroit schools; his mother, Bessie Walton McKinney, was an organist. Ten children came out of that household, seven boys and three girls, and nine of them played. Pianist Harold McKinney, later a fixture of Detroit jazz education, was his brother, as were bassist Ray McKinney and drummer Earl McKinney; his sister Carol played reeds. The siblings worked as a family combo in Detroit before any of them left town. Bernard went to Northwestern High School and then to Wayne State University, where he took coursework in composition and theory until 1955 before quitting to work full time on the bandstand. He is the uncle of R&B producer and pianist Carlos "Los Da Mystro" McKinney.

His first professional jobs came in 1951, alongside Barry Harris and Sonny Stitt, and he spent much of the early 1950s in bassist Alvin Jackson's band. By the middle of the decade he had worked with Art Blakey. His recording career opens with a hometown date: on August 23, 1955, at Detroit's New World Stage Theatre, he played euphonium on Donald Byrd's Byrd Jazz for Tom Wilson's Transition label, in a band with Yusef Lateef on tenor, Barry Harris on piano, Alvin Jackson on bass, and Frank Gant on drums. Two years later, on November 19, 1957, he was at Rudy Van Gelder's Hackensack studio for Pepper Adams's The Cool Sound of Pepper Adams (Regent MG 6066), a quintet with Hank Jones on piano, George Duvivier on bass, and Elvin Jones on drums. Pairing euphonium with baritone saxophone across the front line gave that record a low, dark blend with no precedent in hard bop. He returned to Van Gelder's on June 11, 1959, for the Yusef Lateef session that Savoy split across two albums, The Dreamer and The Fabric of Jazz, and he moved to New York City with Lateef later that year.

New York put him straight into the brass sections that needed a middle voice. He joined Slide Hampton's octet for Slide Hampton and His Horn of Plenty (Strand, 1959) and Sister Salvation, cut at Bell Sound on February 11 and 15, 1960 for Atlantic, both bands stacked with young players including Freddie Hubbard, Booker Little, and George Coleman; he stayed with Hampton in New York into 1963. On June 30, 1960, he was on stage at Freebody Park with the Art Farmer and Benny Golson Jazztet at the Newport Jazz Festival, playing trombone and euphonium in a lineup that also carried Duke Pearson on piano. On August 21, 1961, at Van Gelder's Englewood Cliffs studio, he took the euphonium chair on Freddie Hubbard's Ready for Freddie (Blue Note BLP 4085) beside Wayne Shorter, McCoy Tyner, Art Davis, and Elvin Jones, an album Scott Yanow later listed among seventeen essential hard bop recordings. Seven weeks after that, on October 10, 1961, he recorded in Newark with the pared-down Arkestra that had just relocated from Chicago, playing trombone and euphonium on The Futuristic Sounds of Sun Ra for Savoy. DownBeat named him Talent Deserving Wider Recognition in 1964, and from 1963 to 1972 he worked in the Dizzy Gillespie Orchestra and with James Moody.

The name change came out of the same years. Born Bernard Atwell McKinney, he took the name Kiane Zawadi during the civil rights era as a statement of Black consciousness, and the record credits follow the shift across the mid-1960s: sessions through 1961 are billed to Bernard McKinney, while everything from the March 18, 1966 date onward carries Kiane Zawadi. That March 1966 session, at Van Gelder's, was Hank Mobley's A Slice of the Top, an unusually large Blue Note band with Lee Morgan on trumpet, Howard Johnson on tuba, James Spaulding on alto, McCoy Tyner, Bob Cranshaw, and Billy Higgins, arranged by Duke Pearson around a euphonium-and-tuba bottom. Blue Note shelved it for thirteen years and did not release it until 1979. He also appears across Freddie Hubbard's Blue Spirits (recorded February 1965 and March 1966, released 1967) with Joe Henderson and Larry Ridley on two of its tracks, and on Hubbard's Atlantic date High Blues Pressure, recorded November 13, 1967, where he is credited on both trombone and euphonium.

The 1970s were his busiest decade and his most political. He played trombone in the brass choir on Archie Shepp's Attica Blues, recorded January 24 to 26, 1972 at A&R Recording for Impulse!, a record written in direct response to the Attica prison uprising. He took the euphonium part on McCoy Tyner's Song of the New World (Milestone, recorded April 6 and 9, 1973), in a brass and reed section that included Julius Watkins and Jon Faddis, and recorded with Abdullah Ibrahim on African Space Program the same year. Strata-East, the musician-owned label, used him repeatedly: Harold Vick's Don't Look Back (recorded November 1974, with Sam Jones and Billy Hart) and Charles Tolliver's big-band Impact, recorded January 17, 1975, whose reed section included Charles McPherson. He toured and recorded with Aretha Franklin from 1973 to 1976, received a National Endowment for the Arts grant in 1977, and from 1978 played the Broadway pit orchestra for Bob Fosse's Dancin'. Session work of the period runs from Grant Green's Easy and Les McCann's Another Beginning to Ralph MacDonald's Sound of a Drum and Phyllis Hyman's debut.

He kept working steadily into his sixties and seventies. He worked repeatedly with Frank Foster's Loud Minority, from Manhattan Fever in 1968 through Bursting Out! in 1978 and the archival Well Water, and joined the Frank Foster Big Band in 1981. He held a chair in the Illinois Jacquet Big Band from 1984 to 1987, documented on Jacquet's Got It! (Atlantic, 1988) and on six volumes of Village Vanguard tapes issued much later as The Jacquet Files; he played euphonium in the Clifford Jordan Big Band, including the October 7, 1991 night at Condon's released as Down Through the Years; and he turned up on Joe Henderson's Grammy-winning Big Band in 1996 and Patience Higgins's Live in Harlem in 1998. Away from the bandstand he taught: as a performer and workshop instructor with Jazzmobile, and as an instructor at the New Muse Community Museum in Brooklyn. He co-founded the Collective Black Artists and, later, the Central Brooklyn Jazz Consortium. He married Ima Polly Vann on December 29, 1969, after meeting her in Detroit at the World Stage through trumpeter Donald Towns. Kiane Zawadi passed away on May 21, 2024, at New York Methodist Hospital in Brooklyn, aged 91, survived by his wife Ima, son Kiambu, daughter Kaia, and sister Carol Robinson.

The euphonium is the reason his name comes up at all in instrument histories: a conical-bore tenor brass instrument built for concert bands, almost never carried into a jazz rhythm section, and Zawadi is one of a handful of players ever to solo on it in a jazz context. What he offered arrangers was a voice that sits between trombone and tuba with none of the trombone's edge, and the writers who used him understood exactly that. Pepper Adams set it against baritone saxophone in 1957; Slide Hampton and Duke Pearson buried it inside octet and nonet voicings; McCoy Tyner and Charles Tolliver used it to thicken a brass choir without adding brightness. On Ready for Freddie he is a soloist rather than a texture, and the record is the strongest single argument for the instrument's viability in hard bop. He was equally employable on trombone, which is what kept him in big-band sections for forty years, from Dizzy Gillespie through Illinois Jacquet. DownBeat's 1964 Talent Deserving Wider Recognition award is the only significant critical honor his career attracted, and the description stayed accurate for the next sixty years: colleagues quoted after his death, among them Benny Golson and Bill Saxton, described a musician who taught and supported without flaunting what he knew.