Tench played piano from an early age. His first recital was at age six. After discovering the music of The Beatles, he ended his classical piano lessons and focused on rock and roll. At age 11, he met Tom Petty for the first time at a Gainesville music store. Petty and Tench played together as members of The Sundowners in 1964. The Tench family’s garage was a frequent practice site for the band on evenings when Tench’s father was not present. Tench’s mother enjoyed having the boys there, but would check with the neighbors to make certain the music was not disturbing them.

Songs written by Tench and recorded by other artists include “You Little Thief”, a top 5 UK and Australian hit for Feargal Sharkey in 1985, and “Never Be You” (co-written with Petty), which became a #1 US Country hit for Rosanne Cash, also in 1985. Tench has received two ASCAP songwriting awards: in 1995 for “Stay Forever” (performed by Hal Ketchum) and in 2001 for “Unbreakable Heart” (performed by Jessica Andrews). This was also recorded by Carlene Carter in the early 1990s. He also wrote songs for Kimmie Rhodes (“Play Me A Memory”) and Lone Justice (“Sweet, Sweet Baby (I’m Falling)”).

In 1991, Tench married Canadian model Courtney Taylor. They divorced in late 1999. In 2015 Tench married his second wife, author Alice Carbone Tench. Benmont and Alice welcomed their first daughter, Catherine Gabriella Winter, on December 16, 2017.

In 2008, Tench became part of a supergroup, initially named The Scrolls, now officially known as Works Progress Administration (W.P.A.). The band is composed of Tench, Sean Watkins (guitar), Sara Watkins (fiddle), Glen Phillips (guitar, vocals), Luke Bulla (fiddle), Greg Leisz (various), Pete Thomas (drums), and Davey Faragher (bass). The group released a self-titled album in September 2009. Tench penned one of the songs on the album, named “The Price,” sung by Sara Watkins and himself.

In 2009, Tench frequently appeared with the Watkins Family Hour at Largo at the Coronet in Los Angeles. He has also appeared at the Largo and at the Fillmore in San Francisco as a special guest with Gillian Welch and David Rawlings, and accompanied the Dave Rawlings Machine on part of their west coast tour in spring 2010. In 2015, the Watkins Family Hour released their debut album and went on a national tour.

In 2014, Tench released his first solo album, entitled You Should Be So Lucky. Tench also added keyboard parts to Stevie Nicks’ album 24 Karat Gold: Songs from the Vault.

In 2016, he played the Fleetwood Mac tribute at the Fonda Theater, in Los Angeles; he performed the song “Silver Springs” with Courtney Love. Tench also appears on the bill for a tribute to the band Big Star that took place in Los Angeles, CA, in April 2016 (together with members of R.E.M, Wilco and Semisonic). Tench also reunited with Mudcrutch to record the band’s second album, Mudcrutch 2. The band embarked on their American tour on May 26, 2016.

In March 2019, Tench played 3 shows with Phil Lesh & Friends at the Capitol Theatre in Port Chester, New York. He also played on three songs from The Who’s album WHO, released in December 2019.