Former public servant Candice Burch has been elected to the Legislative Assembly to fill a casual vacancy in the electorate of Kurrajong.
Ms Burch replaces another Liberal MLA, Steve Doszpot, who died last month.
She has held senior roles in the Australian Public Service, including as assistant director at the Department of Finance, before leaving five months ago.
Canberra's newest MLA said housing affordability and cost-of-living pressures on young people would be high on her list of priorities.
"Obviously over recent years we've seen our rates going up and up and up while local services are getting worse and worse," she said.
"That's something I think is really important for the ACT Government to be focused on — those core priorities of Canberrans."
Ms Burch said it was not easy to be taking the seat in such difficult circumstances, but it was something she had "worked hard towards over recent years".
Liberal leader Alistair Coe added they were also honouring Mr Doszpot, who had served since 2008.
"Of course the circumstances for why this vacancy is here is still very raw," Mr Coe said.
"We very much miss Steve Doszpot, he was a great Canberran and he served the Assembly with distinction.
"So we certainly remember and honour him on this day as well."
Ms Burch's term will begin at midnight on Thursday, while an official swearing in will be conducted at the Assembly's next sitting on February 13.
