Harry Allen was born October 12, 1966, in Washington, D.C., the son of big-band drummer Maurice Allen. His father introduced him to jazz before he was old enough for kindergarten, playing him records by tenor saxophonist Paul Gonsalves that left a lasting impression. The family later settled between Los Angeles and Burrillville, Rhode Island, where Allen started on accordion at seven before switching to saxophone at twelve, studying locally with Art Pelosi and Ted Casher.

He attended Rutgers University from 1984 to 1988, taking lessons from Bob Mintzer and John Purcell and playing for several years in Sahib Shihab's big band — Shihab never formally taught him, but the bandstand time under a bebop veteran of his stature mattered as much as any lesson. Allen earned his Bachelor of Arts in music in 1988. While still a student, he got his first real break when bassist Major Holley brought him in to replace an unavailable Zoot Sims on a studio date alongside pianist John Bunch, trombonist George Masso, guitarist Bucky Pizzarelli, and cornetist Ruby Braff — a lineup of swing-era veterans that set the direction his own career would take.

Allen recorded his debut as a leader, How Long Has This Been Going On?, on June 30, 1988, released the following year on Progressive Records with Keith Ingham on piano, Major Holley on bass, and Oliver Jackson on drums. The record announced a fully formed stylist barely out of college: a warm, vibrato-rich tenor sound built on Coleman Hawkins, Ben Webster, Stan Getz, Illinois Jacquet, and Lester Young rather than on Coltrane, Archie Shepp, or Ornette Coleman, whose innovations he has generally sidestepped. British critic Dave Gelly grouped Allen with fellow swing revivalist Scott Hamilton in 2004 as among "the finest exponents of swing tenor alive today," and by 2008 critic C. Michael Bailey was calling him the "Frank Sinatra" of the tenor saxophone — a master interpreter of the American songbook rather than an innovator chasing new vocabulary.

The 1990s and 2000s produced a remarkably steady run of leader dates, many for the Japanese wing of BMG/Novus: Harry Allen Meets John Pizzarelli Trio (1996), Here's to Zoot (1997, a tribute to Zoot Sims recorded with Dave McKenna), Day Dream (1998, with Tommy Flanagan), Harry Allen Plays Ellington Songs (2000, with Bill Charlap), the Cole Porter Songbook (2001, with Benny Green and Russell Malone), I Love Mancini (2002, arranged for strings by Kenny Werner), and Isn't This a Lovely Day (2004, with Hank Jones). Three of his albums earned Gold Disc Awards from Japan's Swing Journal magazine, and Tenors Anyone? additionally won the magazine's New Star Award.

A Brazilian and bossa nova thread runs through the catalog almost as consistently as the standards work. Eu Não Quero Dançar ~ I Won't Dance (1998) paired him with guitarist and vocalist Dori Caymmi, drummer Duduka Da Fonseca, and pianist Larry Goldings; Dreamer (2001) reunited him with Caymmi inside a string-and-cello arrangement; Viva! Bossa Nova (2008) and Copacabana (2010, with bassist Nilson Matta) pushed further into the idiom; and Something About Jobim (2015), recorded with vocalist Joyce and pianist Helio Alves, was built entirely around lesser-known Antonio Carlos Jobim material. Allen has also toured and recorded with the Trio da Paz rhythm section of Romero Lubambo, Nilson Matta, and Duduka Da Fonseca.

Twin-tenor recordings with Scott Hamilton form another throughline, rooted in a chance teenage sit-in with Hamilton at a Newport Jazz Festival appearance by George Wein's Newport All-Stars: Heavy Juice (2004, Concord Jazz) and 'Round Midnight (2012, Challenge Records) both pair the two saxophonists directly. A parallel duo record with baritone saxophonist Joe Temperley, Cocktails for Two, was recorded live at Denver's Rocky Mountain Jazz Party in October 2006 and released in 2007; the Harry Allen–Joe Cohn Quartet, a longtime working group with guitarist Joe Cohn, won the New York Nightlife Award for Outstanding Jazz Combo Performance in 2006 and was nominated the same year for a Jazz Journalists Association award.

Later career highlights include a run of trio records for Posi-Tone with pianist Ehud Asherie (Modern Life, Upper West Side, Lower East Side); For George, Cole and Duke (2014, with Nicki Parrott and Ehud Asherie); Dear Old Stockholm (2016), billed to pianist Vladimir Shafranov with Allen as featured guest; and Under a Blanket of Blue (2020), a trans-Atlantic pandemic-era collaboration recorded remotely with Australian guitarist Dave Blenkhorn — Allen in New York, Blenkhorn in Bordeaux — that became a top-three finalist for France's Académie du Jazz Prix du Jazz Classique. More recent releases include My Reverie by Special Request (2022, again with Blenkhorn), the duo record Live at Bird's Eye (2022, with pianist Martin Sasse), and It Takes 3 (2025, with Rossano Sportiello and Bryan Carter).

Across more than 30 years as a leader, Allen has additionally performed and recorded as a sideman with jazz greats including Kenny Burrell, Herb Ellis, Ray Brown, whose own career is covered in full in his JazzProfiles.com profile, and Hank Jones, as well as with John Colianni and Keith Ingham. He was inducted into the Jazz Monsters Hall of Fame at Soka University of America in 2020 and the Rhode Island Music Hall of Fame in 2024, the latter citing his early Rhode Island study with Art Pelosi and Ted Casher and his sideman work with Major Holley, George Masso, Ruby Braff, and Bucky Pizzarelli. He also won the New York Nightlife Award for Best Jazz Solo in 2010. Now based in North Bergen, New Jersey, Allen continues to tour and record prolifically.

A swinging, ballad-focused tenor stylist in the direct lineage of Coleman Hawkins, Ben Webster, and Stan Getz, Allen has built his career on mainstream, standards-based jazz rather than the modern and avant-garde schools of his generation — a stylistic choice, not a limitation, that critics have repeatedly framed as mastery of interpretation over innovation. That same sensibility extends naturally into the Brazilian and bossa nova repertoire that runs through his catalog: the warm, vibrato-rich tone that serves a Gershwin ballad serves an Antonio Carlos Jobim melody just as well. He is frequently paired in critical writing with fellow swing-tenor revivalist Scott Hamilton, and the two have recorded together directly on more than one occasion, including a pairing rooted in Allen's own teenage encounter with Hamilton on a Newport Jazz Festival bandstand.