On 26 November 2016, Roestbakken made her professional debut aged 15 in a W-League match against the Newcastle Jets. In Canberra's next match, Roestbakken came on as a half-time substitute and became the second-youngest goalscorer in W-League history when she netted an 83rd-minute winner in a 2–1 victory over Melbourne City.[2] She continued to play as part of the Canberra United Academy side in the NPLW Capital Football league, captaining the team to a Federation Cup Final in 2018.[3] By the beginning of her third season, a high level of roster turnover meant she was the second longest serving Canberra player that season behind Nickoletta Flannery.[4]
In December 2018, Roestbakken was nominated for the W-League young footballer of the year,[5] eventually winning the award.[6]
For the 2019-20 season, Roestbakken was appointed the co-captain of Canberra United alongside Nikola Orgill. She was 18 years old at the time of the appointment.[6]
LSK Kvinner
In April 2020, Roestbakken transferred to the Norwegian champions, LSK Kvinner FK. Although due to the COVID-19 pandemic there was uncertainty about when she could join her new team due to the border closures.[7]
She debuted for the Norwegian club in the first game of the 2020 Toppserien season on 3 July, playing the full 90 minutes against Rosenborg.[citation needed]
On 6 June 2019, Roestbakken was promoted from the standby list to the senior Australia squad for the 2019 World Cup, replacing the injured Laura Alleway.[12] Her U20 manager, Gary van Egmond, also acts as assistant with the senior team and had previously hinted at her chances of making the squad despite being uncapped, praising the teenager's work rate, technique and desire for the game.[13][14] She made her senior debut as a stoppage time substitute in Australia's second group game of the World Cup, a 3–2 victory over Brazil.[15]