Borg began his career at BHP Billiton, firstly as a legal officer and then project engineer. He then moved to Freehills in 1998, Mallesons in 1999 and to Hong Kong in 2002 where he joined Mayer Brown JSM. He joined Pinsent Masons in 2004.

Borg has extensive construction and contract administration experience and his major clients include Acciona, Downer, Maeda-Hitachi-Yogogawa-Hsin Cong, China State, Leighton Asia, Wind Prospect, Cathay Pacific and Transfield Obayashi.