Gillett had already officiated games in all three Divisions of the Football League, but entered the history books when he blew the whistle at Vicarage Road, refereeing Watford v Newcastle this term.
Here are five things you should know about the one from the Land Down Under.
WHERE IT ALL STARTED
Gillett got involved with A-League Men, the elite-level men's league in Australia and New Zealand where he refereed five Hyundai A-League Grand Finals from the years 2012 to 2018.
The 34-year old was named the Hyundai A-League Referee of the Year on five occasions before and when he had won the award in 2016/17, it made him the most successful referee in A-League history.
Prior to heading to England, Gillett also officiated in the J-League (top division of Japan Professional Football League), the Indian Super League, the Chinese Super League and the Saudi Professional League - this man has been all over the world.
MIC'D UP
Gillett became a topic of debate in March 2019, when the Australian wore a microphone for his final game in the A-League, allowing television viewers to listen to everything he said.
Gillett talked viewers through his decisions during the match between Melbourne Victory and Brisbane Roar.
He could be heard offering assurances and directions to the players and he scolded Tobias Mikkelsen saying: "If it is not your free-kick then move away from the ball.'
It drew widespread praise!
VAR EXPERT?
Before Gillett was upgraded to the Premier League's referee pool he was a VAR official.
He was among the first referees trained in VAR technology in 2017, as the A-League the first top-flight division to adopt the innovations and was considered an expert in the field.
However the Aussie was under-fire when he found himself the target of an angry Scott Parker who felt the use of VAR was poor.
During the Fulham v Tottenham clash in March earlier this year, a VAR review overturned what would have been a crucial goal in The Cottagers 1-0 loss.
Gilet was in the VAR booth and ruled a handball against Mario Lemina in the build up to Josh Maja's strike.
But Gillett was at the centre of a contentious call in the Premier League on Sunday morning as Brighton came from behind to beat Burnley 2-1.
James Tarkowski headed home a corner for the Clarets, but Brighton were convinced that Neal Maupay was fouled in the build-up. It clearly looked like a big shove on the Frenchman.
EDUCATION FIRST
Gillett moved to the UK to continue his research at Liverpool's John Moores University, after completing a PhD in biomechanics.
He has continued his research into children with Cerebral Palsy, while working his way up in the refereeing ranks.
ON THE FAST-TRACK
Within only a few weeks of arriving in England, Gillett was enlisted as a fourth official at a Liverpool legends exhibition match at Anfield.
Impressing the board, he became an EFL referee, taking charge of a League Two clash between Morecambe and Cheltenham just three weeks after officiating at Anfield.
At the end of that campaign, Gillett was chosen to referee Blackburn against Swansea in the Championship, leading the Australian to be in charge of 64 EFL games by the end of the 2020-21 season - the rest is history!