In the National Women's Rugby Championship, Boyle played for the ACT Brumbies, making her debut in 2016.[3] At the age of 19, she was called up to the Australia women's national rugby union team, known as the Wallaroos, for the 2017 Women's Rugby World Cup in Ireland. Elliott was the youngest player to be selected.[2] She had impressed while playing for the team in the Four Nations tournament, which the Walleroos officials stated was the reason for her selection at the World Cup.[4]
In 2019, Elliott returned to rugby league, joining the Burleigh Bears in the South East Queensland women's division.[6] In May 2019, she represented South East Queensland at the NRL Women's National Championships.[7] On 21 June 2019, she made her debut for New South Wales in its 14–4 win over Queensland.[8] In July 2019, she signed with the Brisbane BroncosNRL Women's Premiership team.[9]
In Round 1 of the 2019 NRL Women's season, Elliott made her debut for the Broncos in their 14–4 win over the St George Illawarra Dragons. On 6 October 2019, she started at prop in the Broncos' 30–6 Grand Final win over the Dragons.[10]
In October 2019, she represented Australia at the World Cup 9s tournament.[11] On 25 October 2019, she made her Test debut for Australia in its 28–8 win over New Zealand.[12]
On 25 October 2020, she started at prop in the Broncos' 20–10 Grand Final win over the Sydney Roosters.[13]
In late September 2022, Elliott was named in the Dream Team announced by the Rugby League Players Association. The team was selected by the players, who each cast one vote for each position.[17]
On 2 October 2022, Elliott captained the Knights in their 32–12 NRLW Grand Final win over the Parramatta Eels.[18]
On 6 October 2024, Elliott started at prop in their 32–28 NRLW Grand Final win over the Cronulla Sharks.
Controversy
On 26 August 2021, Elliott was sanctioned by the NRL after an alleged incident with her future husband Adam Elliott, who was then a Canterbury-Bankstown player.
Millie Elliott was alleged to have met Adam Elliott at a Gold Coast restaurant, where the pair entered the men's toilet and started kissing, with Adam Elliott removing his shirt, before both were ordered to leave the premises.
Millie Elliott was issued a warning by the NRL for her conduct, and was given education and training regarding the obligations of NRL and NRLW players in public, while Adam Elliott was deemed to be the instigator and was fined $10,000 for failing to comply with biosecurity protocols (related to Covid-19) and bringing the game into disrepute.[20]
