In the 1980s, Formanek worked as a sideman with Freddie Hubbard, Joe Henderson, Dave Liebman, Fred Hersch, and Attila Zoller. His debut release as a leader was 1990's Wide Open Spaces, featuring saxophonist Greg Osby, violinist Mark Feldman, guitarist Wayne Krantz and drummer Jeff Hirshfield. In 1992 he released Extended Animation with the same ensemble, except with Tim Berne replacing Osby on sax.
In 1993 Formanek, Berne and Hirshfield recorded as a trio on the album Loose Cannon. Following this, Formanek led the septet of himself, Berne, trumpeter Dave Douglas, reed player Marty Ehrlich, trombonist Kuumba Frank Lacy, drummer Marvin Smith and pianist Salvatore Bonafede. That same year, Formanek began playing with Berne's ensemble Bloodcount through the end of the decade, on the releases Lowlife, Poisoned Minds, Memory Select, Discretion, and Saturation Point. His fourth album for Enja Records followed in 1996, with Douglas, trombonist Steve Swell and drummer Jim Black.
In 1998 Berne and Formanek released Ornery People as a duo, and Formanek issued a solo record, Am I Bothering You?. He toured with Gerry Hemingway that same year. 1999 saw Formanek working in a trio with Ehrlich and Peter Erskine on drums. In 2000 he played in the quartet Northern Exposure with Black, Dave Ballou on trumpet and Henrik Frisk on sax.
Alongside this Formanek has done extensive work as a session musician, appearing on records by Jane Ira Bloom, Uri Caine, James Emery, Lee Konitz, Kevin Mahogany, the Mingus Big Band, Scott Fields, the New York Jazz Collective, Daniel Schnyder and Jack Walrath.
Currently Formanek is the Director of the Peabody Jazz Orchestra and the jazz bass instructor at the prestigious Peabody Conservatory of Music in Baltimore, Maryland.
- Wide Open Spaces (Enja Records, 1990)
- Extended Animation (Enja, 1992)
- Loose Cannon (Soul Note, 1993)
- Low Profile (Enja, 1994)
- Nature of the Beast (Enja, 1996)
- Ornery People with Tim Berne (Little Brother, 1998)
- Am I Bothering You? (Screwgun, 1999)
- Relativity (Enja, 1999)
- The Rub and Spare Change (2010 ECM) w/ Craig Taborn, Tim Berne and Gerald Cleaver
- Small Places (2012 ECM) w/ Craig Taborn, Tim Berne and Gerald Cleaver