Walker was born in Scunthorpe, Lincolnshire. He received an LGSM certificate in 1949, ARCM in 1950, a Bachelor of Music from University of Durham in 1956,and a Doctor of Music in 1965. Between 1957 and 1960 he studied privately with Hans Keller, an association which he has always acknowledged as formative. These lessons were resumed, albeit irregularly, once Walker joined Keller at the BBC in 1961.
From 1958-61 Walker lectured at the Guildhall School of Music, having studied piano there with Alfred Nieman, noted for teaching improvisational techniques. He also taught at the University of London from 1954 to 1960. Walker worked at the BBC Radio Music Division as a producer between 1961 and 1971. Seeking to return to his "first love", teaching, Walker gave up radio production and took an appointment as Professor of Music at McMaster University in Hamilton, Ontario, where he chaired the Department of Music 1971-1980 and 1989-1995. In 1981, he was responsible for the establishment at McMaster of the first graduate program in music criticism in Canada. Since 1995, he has been Professor Emeritus at McMaster. From 1984-87, he was a Distinguished Visiting Professor of Music at City University in London.
His three-volume biography of Franz Liszt, which took him 25 years to complete, has been very influential. Common adjectives attached to the work include "monumental" and "magisterial", and it is said to have "unearthed much new material and provided a strong stimulus for further research". Walker himself says that when he found, as a BBC producer compiling notes for program announcers, that "there wasn't a decent book in English on Liszt", he eventually decided to write one himself, but was determined "not to make a major statement that couldn't be supported by documents ... and because Liszt himself was a traveller the archives were everywhere."
The first volume won the James Tait Black Memorial Prize in biography for 1983 and best book on music from the Yorkshire Post Newspapers in 1984. The three-book series was given the Royal Philharmonic Society Book Award in 1998.
TIME Magazine praised the biography as "a textured portrait of Liszt and his times without rival", saying that Walker's work was "equally strong on the music and the life", which discussed Liszt's corpus "with greater understanding and clarity than any previous biographer". The New York Times, reviewing the second volume, tutted of Walker's passion for his subject, "Mr. Walker can see only the good, and will stand for no criticism of his hero", but still called Walker's extensive research "incredible.... Mr. Walker seems to know everything about Liszt, and anything connected with Liszt, during every single day of the long life of that genius." The Washington Post music critic Tim Page, including the third volume in his best books of the year list, called it "unquestionably a landmark" and "meticulously detailed, passionately argued and sometimes wrenchingly moving".
- Honorary Fellow of the Guildhall School of Music, 1974.
- Hungarian Liszt Society Medal, 1980
- American Liszt Society Medal, 1984
- Fellow of the Royal Society of Canada, 1986
- Pro Cultura Hungaria Medal (Government of Hungary), 1995
- Honorary D. Litt (honoris causa) from McMaster University, 2002
- Knight's Cross of the Order of Merit of the Republic of Hungary, 2012
- A Study in Music Analysis, 1962.
- An Anatomy of Musical Criticism, 1966.
- Symposium on Chopin (Editor), 1967.
- Symposium on Liszt (Editor), 1970.
- Franz Liszt: The Man and His Music. New York: Taplinger Publishing, 1970. ISBN 0-8008-2990-5.
- Robert Schumann: The Man and His Music, 1972. ISBN 0-214-66805-3.
- Symposium on Schumann (Editor), 1972.
- Liszt: v. 1. The virtuoso years, 1811-1847. Hardcover publisher Knopf, 1983, Softcover publisher Ithaca: Cornell University Press and revised, 1987. ISBN 0-394-52540-X for all three hardcover. ISBN 0-8014-9421-4 for v. 1 revised.
- Liszt: v. 2. The Weimar years, 1848-1861. Knopf and Cornell University Press (no new material), 1989. Revised ISBN 0-8014-9721-3.
- Liszt, Carolyne, and the Vatican: The Story of a Thwarted Marriage (Co-author, with Gabriele Erasmi). 1991.
- The Diary of Carl Lachmund: An American Pupil of Liszt (Editor), 1995.
- Liszt: v. 3. The final years, 1861-1886. Knopf and Cornell University Press, 1996 and 1997. Cornell edition has ISBN 0-8014-8453-7.
- The Death of Franz Liszt: Based on the Unpublished Diary of his Pupil Lina Schmalhausen (Editor). Cornell University Press, 2002. ISBN 0-8014-4076-9.
- Reflections on Liszt, 2005.
- Hans von Bülow: a Life and Times, OUP, 2009.
- 'Schoenberg’s Classical Background', Music Review, xix (1958), 283–9.
- 'Aesthetics versus Acoustics', The Score, No.27, July 1960.
- 'Back to Schönberg', Music Review, xxi (1960), 140–47.
- 'Liszt and the Beethoven Symphonies', Music Review, xxxi (1970), 302–14.
- 'Liszt’s Duo Sonata', Musical Times, cxvi (1975), 620–21.
- 'Schumann, Liszt, and the C major Fantasie, op. 17', Music and Letters, vol. 60, 1979.
- 'Music and the Unconscious', British Medical Journal, 22 December 1979.
- 'Personal View [Infant prodigies]', British Medical Journal, 13 September 1980.
- 'Liszt and Vienna', New Hungarian Quarterly, No.99 (1985), 253–9; repr. in Journal of the American Liszt Society, No.xix (1986), 10–20.
- 'A Boy Named Daniel', Hungarian Quarterly, vol. 27, Autumn 1986.
- 'Liszt and Agnes Street-Klindworth: A Spy in the Court of Weimar?', Studia Musicologica Academiae Scientiarum Hungarica, vol. 28, 1986.
- 'Schopenhauer and Music', The Piano Quarterly, vol. 144, Winter 1988-89.
- 'Liszt and the Schubert Song Transcriptions', Musical Quarterly, lxvii (1981), 50–63; lxxv (1991), 248–62.
- 'Joukowsky’s Portraits of Liszt', Hungarian Quarterly, vol. 34, Summer 1993.
- 'Liszt and his Pupils', Hungarian Quarterly, vol. 36, Summer 1995.
- 'Tribute to Hans Keller', Canadian University Music Review, xvii (1996), 118–28.
- 'Liszt and the Lied'”, Hungarian Quarterly, vol. 37, Winter 1996.
- "Ernst von Dohnányi (1877-1960): A Tribute", Hungarian Quarterly, vol. 43, Spring 2002.
- "Dohnányi Redeemed", Hungarian Quarterly, vol. 43, Autumn 2002.
- "Walker, Alan". Encyclopedia of Music in Canada. Retrieved 2006-12-07.
- Stige, Brynjulf (1999). "Healing Heritage: Exploring the Tonal Language of Paul Nordoff". Nordic Journal of Music Therapy. 8 (2): 214–217. Archived from the original on 2006-10-16. Retrieved 2006-12-07. Via Barcelona Publishers website.
- "Alan Walker: Finding Aids". The William Ready Division of Archives and Research Collections, McMaster University. Archived from the original on 6 November 2006. Retrieved 2006-12-07.
- "Dr. Alan Walker". McMaster University. Archived from the original on 2007-02-07. Retrieved 2006-12-07.
- "Four to receive honorary doctorates at Fall Convocation November 9". McMaster University. November 5, 2001. Archived from the original on 2006-06-28. Retrieved 2006-12-07.
- Zimdars, Richard (2004). "Book Review The Death of Franz Liszt". American Music Teacher.
- Hamburger, Klára (2005). "Death in Bayreuth: An Unknown Document about the Death of Franz Liszt" (Winter). Hungarian Quarterly. Archived from the originalon 2007-03-20. Retrieved 2006-12-07.
- "The Cambridge Companion to Liszt". Cambridge Companions to Music. Cambridge University Press. Retrieved 2006-12-07.
- "The Prize Winners". University of Edinburgh. Archived from the original on 15 January 2007. Retrieved 2006-12-07.
- "RPS Music Awards". Royal Philharmonis Society.
- Ravetz, Elliot (September 2, 1996). "The Book of Liszts: Finally, a Biography that Does Justice to All Facets of Franz Liszt's Messy Life and Protean Work". Time Magazine. Retrieved 2006-12-07.
- Schonberg, Harold C. (July 14, 1989). "Books of The Times; A Scholarly Crusader for Fran Liszt". The New York Times. Retrieved 2006-12-07.
- Page, Tim (1996-12-08). "Informed Opinions: Experts Pick Their Favorites". The Washington Post. Retrieved 2006-12-07.
- "Roots & Legacy: Alan Walker". University of Georgia. Archived from the original on 2007-02-13. Retrieved 2006-12-07. A Celebration of Liszt and Matthay, presented by the American Liszt Society and the American Matthay Association.