A founding member of the jazz fusion group The Shuffle Demons, he has toured Europe and Canada to critical acclaim for over 27 years.

Underhill has performed and recorded with The Neville Brothers/Meters, Han Bennink, Julius Hemphill, Dr. John, Kathleen Edwards, Taj Mahal, Maria Muldaur, Rob McConnell, Molly Johnson, Blue Rodeo, Andy Stochansky, Hawksley Workman, The Sadies, Luke Doucet, Bob Wiseman, Soul Rebels, Kevin Breit, NOMA and Toronto jazz stalwarts like Steve Koven, Tyler Yarema and George Koller.

A session player and sideman, he has written horn and string arrangements for Kathleen Edwards, Molly Johnson, Andy Stochansky, Hawksley Workman, Blue Rodeo, Bob Wiseman, Big Rude Jake and Lorraine Segato.

He leads several diverse groups including his jazz quintet, the Funk Explosion and the improvising electronic groove ensemble Astrogroove.

Underhill performed Van Morrison's Into the Mystic at the state funeral for Jack Layton, deceased New Democratic Leader of the Official Opposition, on August 27, 2011.