Ms Sharkie was a British citizen at the time of her 2016 nomination.
Nick Xenophon Team MP Rebekha Sharkie has spoken to the prime minister about her eligibility to sit in parliament.
Ms Sharkie, who was born in the UK and migrated to Australia when she was one-year-old with her parents, said she completed forms to renounce her British citizenship on April 19 last year, weeks before the July 2 federal election.
She sent the documents off by express post to the UK and the UK Home Office acknowledged her application on June 2.
Ms Sharkie then nominated for the seat of Mayo "about June 7" before the office registered her renunciation.
The MP said she had spoken to Malcolm Turnbull about the matter and in that conversation he had told her she may have to refer herself to the High Court.
"I have been open throughout about my citizenship status and have supported a full audit of all members of parliament on this issue," Ms Sharkie said in a statement.
"I believe that I took all steps that were required by the UK to renounce any entitlement to UK citizenship, that were within my power to do so.
"I had no control as to the speed at which the UK Home Office processed my application, but I note that well over a month would have passed before I actually nominated for the seat of Mayo."
Ms Sharkie said she had already spoken to Nick Xenophon who was deemed eligible to sit in parliament by the High Court after he found out he was a British citizen by descent.
She added she would respect the citizenship process but was 'confident' she had complied with Section 44.
"In the meantime I will continue working hard, seven days a week, to deliver for the people of Mayo," she said.