As a grade schooler in his native Melbourne, Grunwald learned guitar and bass from his grandfather. That started an obsession with the blues, which expanded into an expertise as he took in blues shows on the city's community radio stations during his teens. By his early twenties, Grunwald had been in and out of several bands, including the Blue Grunwalds and the Groove Catalysts. He ultimately preferred playing solo, however, and booked small shows along the coastline wherever there was a good beach for surfing, even if it meant playing unnoticed for hours in the corner of a restaurant.
Still without a manager, he recorded a set of his songs and several blues covers live (including songs by Howlin' Wolf and Robert Johnson), self-releasing Introducing Ash Grunwald in 2001. Shortly after that, he discovered Tom Waits, in particular his work from the '80s and after, which involved experimental percussion with everything from pots and pans to a dumpster. In 2004, Grunwald recorded a second album, I Don't Believe, again live in the studio and solo, this time using spanners and hammers for percussion and adding several covers of Waits' songs. It was also the first time he used samples and live loops on an album. I Don't Believe was nominated for an ARIA Music Award for Best Blues & Roots Album. Songs from those first two records were then combined on 2005's Live at the Corner, which won him an Australian Blues Award for Album of the Year in addition to another ARIA nomination. In the meantime, the popularity of blues and roots had exploded in Australia with independent musicians like the John Butler Trio suddenly capable of topping the charts, and Grunwald was caught up in the boom. The JJJ radio station was responsible for spearheading the trend, and in 2005, Grunwald's youthful fascination with radio came full-circle when he became host of JJJ's Roots N All show, a position he held for 18 months. During that time, he also worked on Give Signs, his first album to consist only of original songs. After arriving on his own Delta Grooves Records label in mid-2006, it earned him a third ARIA nomination and marked his first appearance on Australia's album chart, where it peaked at number 84. As part of Mushroom Publishing's annual songwriting workshop, Grunwald teamed up with Count Bounce of hip-hop group TZU with the goal of creating a song in a day. The two had a passing acquaintance from sharing the bill at festivals, but after working together for the workshop, they collaborated on Grunwald's 2008 album, Fish Out of Water. It was Grunwald's first time recording with anyone else and in more traditional studio sessions, as opposed to tracking everything live. It reached the number 43 spot on the album chart in Australia and resulted in another ARIA Music Award nomination. That year, he also issued the live set Live from the Factory.
Following early 2010's Live at the Fly by Night, he received his fifth ARIA nomination for Best Blues & Roots Album for that June's Hot Mama Vibes. Featuring the song "Walking" from the soundtrack to the Bradley Cooper-Robert De Niro film Limitless, it climbed to number 31 in Australia. He had his highest-charting album yet with his sixth studio long-player, 2012's Trouble's Door, which he called his most personal work to that point. It peaked at number 29 on the ARIA album chart.
Grunwald next teamed up with former cover-group bandmate Scott Owens and drummer Andy Strachan (the Living End, Pollyanna) for set of covers alongside two original songs. The resulting Gargantua included versions of Gnarls Barkley's "Crazy" and Howlin' Wolf's "Smokestack Lightning" and hit number 46 in Australia. He followed that with an appearance at the number 52 spot with 2015's Now, an amplified mix of swamp rock, blues, and swagger. After a decade on Delta Grooves, he made his debut on Bloodlines Records with the collaborative Mojo in 2019. With production by Grunwald, Carla Olson, and Brian Brinkerhoff, and appearances by nearly a dozen featured guests, it returned him to Australia's Top 40. ~ Marcy Donelson & Jody Macgregor, Rovi