Holt joins Firefly on 2 May as one of the agency's five board members, and will report to MD Mark Mellor and CEO and founder Claire Walker.
Motorola, one of Firefly's flagship accounts, will be among the clients Holt will oversee.
Mellor has hailed Holt's 'broad skills across business-to-business, technology and corporate', including his experience in working for 'plenty of the mainstream brands'.
During his tenure at Cancan, where clients included BMW/Mini, Holt served as a non-executive director at tech agency Prodigy Communications.
Prior to joining Cancan, Holt worked in an interim senior management role at Bite Communications, where he handled the Apple and Yahoo! accounts.
He also acted as outsourced EMEA PR manager for Sun Microsystems and previously had spells as head of technology at Golin Harris and Edelman. To Firefly he follows Brandon Stockwell, who joined the agency in November as head of consumer (PRWeek, 25 Nov 2005). Stockwell previously spent six years at Cohn & Wolfe.
Firefly last month also appointed ex-GCI Europe chairman Adrian Wheeler as a non-executive director. Wheeler participates in 'quarterly strategic board meetings' but is not attached to specific clients. In January the agency won the comms account for computer services group Getronics, thereby ending the Dutch company's six-year relationship with Kinross & Render.
Firefly associate director Robin Wilson quit last month to join Bite Communications. Holt inherits many of Wilson's responsibilities, albeit holding a more senior position.