The Democratic Unionist Party has backed a deal to support the minority Tory government currently in power.
Talks between the Conservatives and the DUP had been ongoing for almost three weeks since the general election delivered a hung Parliament.
The agreement was signed by Tory chief whip Gavin Williamson and DUP representative Sir Jeffrey Donaldson in the presence of Prime Minister Theresa May and DUP leader Arlene Foster, who said she was "delighted" an arrangement had been agreed .
Speaking at No.10, Mrs May said: "We share many values in terms of wanting to see prosperity across the UK, the value of the union, the important bond between the different parts of the UK.
"We want to see this protected and enhanced, and have the desire to see a strong government in place.
"The agreement we have is a very, very good one. We look forward to working with you."