Born in New York City in December 1930, he attended the High School of Music and Art, then Queens College, and did graduate work at Princeton University in the early 1950s with Oliver Strunk, Arthur Mendel, and Nino Pirrotta. He was trained as a cellist, studying with Lucien Laporte of the Paganini Quartet, and is still active in chamber music. He was married to Doris Hoffmann Lockwood from 1953 until her untimely death in 1992, and they had two children, Daniel and Alison. In 1997 he married Ava Bry Penman.
Lockwood taught at Princeton University from 1958 to 1980, and at Harvard University from 1980 to 2002. He is currently a Distinguished Senior Scholar at Boston University. He edited the Journal of the American Musicological Society from 1964 to 1967 and was president of the American Musicological Society from 1987 to 1988. In 1984 he was elected to membership in the American Academy of Arts and Sciences, and in 2013 to the American Philosophical Society.
His main fields are the music of the Italian Renaissance and the life and music of Beethoven. In 2003 Joseph Kerman called him "a leading musical scholar of the postwar generation, and the leading American authority on Beethoven."
A festschrift in his honor was published in 1996. The Lewis Lockwood Award of the American Musicological Society, awarded annually to an exceptional book by a musicologist within ten years of his or her Ph.D., is named in Lockwood's honor.
- Beethoven's Symphonies: An Artistic Vision (New York, W. W. Norton, 2015)
- Beethoven's "Eroica" Sketchbook: A Critical Edition: Transcription, Facsimile, Commentary; co-authored with Alan Gosman, 2 vols. (University of Illinois Press, 2013)
- Inside Beethoven's Quartets: History, Performance, Interpretation, co-authored with the Juilliard String Quartet (Cambridge,MA: Harvard University Press, 2008)
- Beethoven: The Music and the Life (New York, W.W. Norton, 2003; paperback 2005); finalist for a Pulitzer Prize in biography; translated into eight languages
- Beethoven: Studies in the Creative Process (Harvard University Press, 1992)
- Music in Renaissance Ferrara, 1400-1505 (Oxford University Press, 1984; revised reprint Oxford University Press, 2008)
- The Counter-Reformation and the Masses of Vincenzo Ruffo (Venice: Fondazione Giorgio Cini, 1970)
In addition, Lockwood is the author of many articles as well as several other publications in both Renaissance and Beethoven studies, and was the founder of the yearbook Beethoven Forum (1992–2008).
- Paula Morgan, "Lewis Lockwood". The New Grove Dictionary of Music and Musicians, online.
- Press Release, "Lewis Lockwood to join the BU Faculty, October 10, 2011"
- Cummings, Anthony M.; Owens, Jessie Ann, eds. (1996), Music in Renaissance Cities and Courts: Studies in Honor of Lewis Lockwood, Detroit Monographs in Musicology, Harmonie Park Press, ISBN 978-0-89990-102-2.
- Lewis Lockwood Award, American Musicological Society, retrieved 2010-04-28.