Mrs Foster joined the DUP in 2004, shortly after resigning from the UUP
BBC news takes a look at the background of the woman who is to take over as temporary First Minister of Northern Ireland, as Peter Robinson tries to clear his name.
Arlene Foster is a fully qualified solicitor from County Fermanagh who joined the Democratic Unionist Party in January 2004, just weeks after resigning from the rival Ulster Unionist Party.
She currently holds three political posts in Northern Ireland.
She is the Minister for the Department of Enterprise, Trade and Investment (DETI) in the Stormont Assembly - a position she has held since June 2008.
She is also an MLA for the Fermanagh South Tyrone constituency and an elected representative of Fermanagh District Council.
The 39-year-old was born Arlene Kelly in July 1970 and, as a child, had first-hand experience of the violence that engulfed Northern Ireland during the Troubles.
A bomb exploded under Arlene Foster's school bus in June 1988
The IRA tried to kill her father, a part-time policeman in the Royal Ulster Constabulary (RUC), while she was a young schoolgirl.
She later described the incident to the Sunday Tribune during the 2005 election campaign.
"They shot him in the head as he was closing in the cattle. He came crawling into the house, blood streaming down his face. We couldn't stay in Roslea. I'd to move house and school - it was traumatic," she told the newspaper.
School bus bomb
As a teenager in 1988, she survived a bomb which exploded under her school bus which which was being driven by a part-time UDR soldier.
She told the same reporter that a girl who had been sitting near her was badly injured in the attack.
She was educated at Enniskillen's Collegiate grammar and went on to study law at Queens University, Belfast.
After qualifying, she then worked as a private practice solicitor in Enniskillen and Portadown for 11 years, before devolution was restored to Northern Ireland in 2007.
In February 2008 she was named as the "Parliamentarian/Assembly Member of the Year" at the Women in Public Life Awards which were held in London.
She is also a mother of three young children under the age of nine and has previously said she had "no difficulty" in balancing her family commitments with her political career.
Arlene Foster is a qualified solicitor and a mother of three young children
Her decision to defect to the DUP six years ago came just weeks after she was elected to the Assembly as a UUP MLA.
She resigned alongside Jeffrey Donaldson and UUP colleague and Norah Beare amid disagreements with the direction the party was taking.
Her role as enterprise minister is her second ministerial post in the Northern Ireland Assembly.
Before the 2008 reshuffle she was the Stormont environment minister, and found herself in the middle of a political storm over the development of a replacement visitors' centre at the site of Northern Ireland's top tourist attraction, the Giants Causeway in County Antrim.
In September 2007, Mrs Foster said she was "minded" to approve a plan for the centre to be built by Seaport Investments Ltd, a company owned by the private developer Seymour Sweeney.
It later emerged that Mr Sweeney had close links to the DUP's Ian Paisley Junior.
Her decision was later reversed and the National Trust is now in the process of building the visitors' centre.