Gavin was admitted to practice in 1997 commencing employment as a plaintiff lawyer with Slater and Gordon lawyers on 1 July 1997 then operating his own firm Workforce Legal from 1 July 2004 with an ex-partner of Slater & Gordon lawyers, Paul Mulvany, former judge of the Accident Compensation Tribunal. Gavin commenced defendant work on 1 September 2010 as a Senior Associate with Hall & Wilcox lawyers until 24 December 2014.

In early 2015 he commenced employment as in-house counsel for Macil Group Investigations overseeing its investigations concerning common law claims and then, as Senior Legal Counsel for WorkSafe Victoria practicing in its Dispute Management Division from 20 June 2017 to 4 March 2018 he provided instructions to Victorian WorkCover Authority panel firms on a range of complex litigious matters.

Gavin commenced employment with Russell Kennedy as Special Counsel in late March 2018 before being promoted to Principal from 1 July 2019 where he continues to practice and manage a range of challenging matters both at common law and in the no fault statutory benefits scheme.