Nettl's research interests varied widely; he wrote on music of the Blackfoot people, Iran, Southern India and particularly the scope and methods of ethnomusicology as a discipline.

His lengthy teaching-career centered on the University of Illinois Urbana-Champaign, where his many students included Stephen Blum and Philip V. Bohlman.

[2] His father was Paul Nettl [de] (1889–1972), a well-known musicologist who researched Mozart as well as the connections between Czech, German and Jewish musical traditions.

[6] The Nettl family, of Jewish descent, fled Europe in 1939 amid Nazi Germany's occupation of Czechoslovakia.

[3][16] Nettl himself cited Blackfeet, Iranian, and Southern Indian music as his fields of expertise, having done fieldwork with all three cultures.

[7] McDonald remarked that Nettl's "most important research contributions, however, involved historicizing the discipline [of ethnomusicology] from its early origins to the present day.

[24] He authored other surveys, such as the Theory and Method in Ethnomusicology (1964) and edited Comparative Musicology and Anthropology of Music (1991), alongside his student Philip V.

[25] Musicologist Jeffrey Sposato, a colleague of Nettl, remarked that "to describe Bruno as a giant in the field of ethnomusicology hardly does him justice.

His work was seminal in establishing the discipline in the United States, both through his research and via the army of ethnomusicologists he has trained over the years".

[26] Several of Nettl's students became important music scholars, Samuel Araujo, Carol Babiracki, Gérard Béhague, Virginia Danielson, Victoria Lindsay Levine, Ali Jihad Racy, Melinda Russell, Margaret Sarkissian, Stephen Slawek, Ted Solis, Christopher Waterman, and notably, Stephen Blum and Philip V.

[3] Nettl met his wife, the artist Wanda Maria White, while he was a student at Indiana University and the couple married in 1952.

[30] He frequently wrote comedic verses for close friends and family; they were collected and published in the anthology Perverse at Eighty (2010), which included drawings by his daughter Gloria.