In an interview with , Jordon Steele-John confirmed he would take up the vacant spot left by former Greens Senator Scott Ludlam, subject to electoral commission approval.
"Scott has been an incredible mentor and friend to me," he said. "So obviously there has been that to deal with, and then I had to really think about my own position.
"After that careful internal reflection - which is appropriate for a significant decision like this - I have firmly resolved that I want to do this job. I'm capable and ready to do this job."
In a statement from Greens WA co-conveners Sarah Nielsen-Harvey and Grahame Bowland, the appointment is now being processed.
"In the event that Jordon Steele-John is elected to the senate as a result of a countback, all support will be given to Jordon in his new role," the statement read.
"Jordon has been an active Greens member for many years, and is well known and respected outside the party for his work in the youth and disability sectors.
"As per the party by-laws, an open preselection will be conducted later this year as was previously planned by the party, to determine our lead Senate candidate at the next federal election."
Mr Ludlam stood down after finding out he was improperly elected more than a decade ago because he held dual citizenship with New Zealand.
Under section 44 of the Constitution, that makes him ineligible to hold office.
Mr Ludlam took Twitter to congratulate his pending replacement.
Born in Britain, Mr Steele-John came to Australia with his parents as a child.
Living with cerebral palsy, his determination to enter politics saw him set up a stall at a Fremantle shopping centre.
Mr Steele-John told Fairfax he was confident he did not have dual citizenship with Britain.
"I was the Greens candidate for Fremantle in 2013 and therefore had to go through that citizenship process then," he said.
Mr Steele-John also shot down speculation that he was pressured to let a more conventional candidate take up Mr Ludlam's vacant seat.
"I have experienced no pressure whatsoever," he said. "I've only experienced the total and complete support of the entire party to come to whatever decision I felt was right for me and for the party."
Mr Steele-John had been studying politics and history at university, but will now ask for a deferral.
He intends to be an active voice in the upper house, fighting for issues surrounding disability and youth unemployment.
