[citation needed] Crumlin serves a Director of the ACTU's Centre for Workers' Capital in Australia and chairs a number of charitable and not-for-profit organisations including the Tas Bull Seafarers Foundation, Hunterlink and the ITF Seafarers Trust, as well as representing workers at the International Labor Organisation on maritime related labour governance matters.

In November 2024, Crumlin was appointed to the board of Cbus[4], the Australian industry superannuation fund for construction workers and their families.

[5] Since the Maritime Union's amalgamation in 2018 with the CFMEU, Crumlin has continued to serve as the division's National Secretary.

[citation needed] Crumlin was elected President of the International Transport Workers’ Federation (ITF) in August 2010[7] – a global union federation of 677 trade unions representing 19.7 million workers in 149 countries in the seafaring, port, road, rail and aviation sectors.

In October 2024, at the ITF's 46th International Congress in Marrakech, Crumlin was elected to another term as President[9].