[4] A child of Italian immigrants from Campania in Southern Italy, Pezzullo was born and raised in the suburbs of St George, Sydney.

[8][13] In July 2009 Pezzullo joined the Australian Customs and Border Protection Service as chief operating officer, a role which he continued in until September 2012.

[17] In April 2021, in an Anzac Day message to staff, Pezzullo said Australia must strive to reduce the likelihood of war "but not at the cost of our precious liberty".

The 42-year-old was charged after an investigation over allegations he sold prescription drugs to fellow Sydney Airport Customs officers and lied to the Australian Commission for Law Enforcement Integrity.

[20] While the case was underway Michael Pezzullo was fulfilling senior executive roles in Customs and Border Protection, but had disclosed the conflict to his minister from the outset.

[21] In a note to staff regarding the case he was reported to have said: "from the outset, I asked and expected to be treated as a detached family member with no official rights, interests or powers in the matter."

[22] On 25 September 2023 Pezzullo stood aside at the direction of then Home Affairs Minister Clare O'Neil pending an investigation following revelations he had made partisan interventions during the 2018 Liberal Party of Australia leadership spills.

[23] Pezzullo is alleged to have unduly influenced this process by communicating his leadership and ministerial preferences to Liberal Party powerbroker Scott Briggs.

[23] Then Home Affairs Minister Clare O'Neil referred the allegations concerning Pezzullo, including the WhatsApp message scandal, to the Australian Public Service Commissioner, Dr Gordon de Brouwer, who then set up an inquiry.

[28] Pezzullo was made an Officer of the Order of Australia (AO) in the 2020 Queens Birthday Honours for "distinguished service to public administration through leadership roles in the areas of national security, border control and immigration".