Larissa Waters will become the first Australian senator to return to parliament after she was booted in 2017 for being a dual citizen.
Greens Senator Andrew Bartlett will step down from the role in August to focus on running for the federal lower house seat of Brisbane at the next election.
His decision paves the way for Ms Waters to return to Canberra in September.
Ms Waters, who has had almost a year away from politics, said she was "tickled pink" by his announcement.
"Andrew's done a really ethical and honourable thing here," she said on Saturday.
"He's standing down to focus on winning Brisbane but he's the first replacement senator who has stood down for the original person and I think that really again speaks volumes for the integrity that the Greens operate with."
Senator Bartlett withdrew from the pre-selection battle for the upper house seat in February.
He also declared his intention to run for Brisbane, but there was no date set for his departure from the Senate.
Senator Bartlett denied it was the intention all along for Ms Waters to return to the upper house once her citizenship issues had been resolved.
"It wasn't a plan," he said.
Senator Bartlett said although it would be a tough ask to oust Liberal incumbent Trevor Evans from the seat of Brisbane, it was possible.
When asked if she had ever considered running for the lower house seat, Ms Waters said no.
"The work that I enjoy doing is working on those big issues that affect all Queenslanders," she said.
She also disputed a suggestion she would have been the best candidate were the Greens serious about winning Brisbane.
"We've got a former senator here who's had more than 11 years in the Senate," she said.
"These are our big guns so to speak, in the peaceful sense of the word."
Ms Waters said upon her return to Canberra her focus would be on cleaning up politics and removing the influence of corporate donors.
She said she did not believe voters would be influenced by the citizenship saga that removed her from the Senate in the first place.
"I think they've got more important issues that they'll be thinking about," she said.
Australian Associated Press
