She said she chose to investigate her status following Mr Joyce's revelation on Monday, and was subsequently told by the UK Home Office that she held British citizenship through her Scottish father.
Senator Nash said based on the advice of the solicitor-general, Prime Minister Malcolm Turnbull had advised there is no need for her to step down as deputy Nationals leader or resign from cabinet.
"Growing up, my parents always told me that I was not a dual citizen", Senator Nash said.
It comes just days after deputy Prime Minister Barnaby Joyce was outed as being a New Zealand citizen, and after Resources Minister Canavan resigned upon finding out he was in fact an Italian citizen last month.
Fiona Nash admits she is a British citizen by descent, becoming the third Australian government minister caught in the country's dual-citizenship crisis.
She has represented the Nationals in the Senate since 2005, and has served as deputy leader of the party since February 2016.
Senator Nash is the sixth MP to be referred to the High Court over dual-citizenship.
Like Mr Joyce, Senator Nash vowed to stay on as a minister, citing legal advice the government had received.
The Oilers agree to a contract of eight seasons in Leon Draisaitl
Beginning in 2018, the captain of the Oilers should be a holder of a pact of eight years, with a total value of $100 million. The deal is a one-year, $1 million contract plus $700,000 in potential performance bonuses, the Wild announced .
Senator Nash, who was born in Sydney in 1965, said she had been raised by her mother.
"I had very little contact with my father throughout his life and he died nine years ago".
The Australian Labor Party has seized on the latest crisis, with Senator Katy Gallagher saying the entire National Party leadership was now facing disqualification from parliament.
If the deputy prime minister doesn't abstain from voting in parliament's lower house when MPs return to Canberra in a fortnight's time, Labor will seek to have all votes deferred until the High Court rules on his eligibility, which could take months.
"This is simply not good enough".
Mr Joyce has since renounced his New Zealand citizenship.
One Nation senator Malcolm Roberts, as well as former Greens senators Larissa Waters and Scott Ludlam, have also been referred to the High Court over dual citizenship.