The leader of the Conservative Party got a rapturous reception UUP conference after hailing his support for the union between Northern Ireland and Britain.
Mr Cameron was the keynote speaker at the UUP annual conference in Belfast to mark the decision of the two parties to form a new political alliance which will see candidates fielded in Northern Ireland on a joint ticket.
The Conservative leader says he wants to give the North's electorate the chance of real influence at Westminster.
Currently the UUP only holds one seat in the House of Commons and its only MP, Lady Sylvia Hermon, is not thought to be in favour of the alliance.
However Ulster Unionist leader Sir Reg Empey says it is fitting that the UK's two oldest political parties should come together to secure Northern Ireland's future within the union.
Mr Cameron told the conference that closer ties between his party and the UUP will benefit Northern Ireland.
The parties have agreed to select joint candidates in European and Westminster elections.
Mr Cameron said the nature of the relationship between the Stormont executive and the Irish Government, was largely due to the UUP.
