Robin Swann has been elected as the new leader of the UUP.
The North Antrim MLA was the only name put forward for the job at a party meeting in Belfast on Saturday morning.
He will take over from Mike Nesbitt, who announced he was stepping down in the wake of the Assembly election.
In his speech Mr Swann said: "This party has a fantastic amount to offer and part of our role is making that union attractive to everybody in Northern Ireland.
"It’s about promoting a positive unionism, a confident unionism and an embracing unionism."
Mr Swann said those who seek a single unionist party should "consider carefully the consequences of such an outcome".
He added: "A single unionist party would limit choice, stifle debate and quickly result in the depletion of Unionist votes at the ballot box.
"I am in the Ulster Unionist Party - we are in the Ulster Unionist Party - because we believe in its vision, its policies and its priorities.
"No other party comes close to representing the brand of Unionism that we have and I believe in."
On the recent election results - which saw the UUP return 10 MLAs down from 16 in the smaller Assembly, making them the fourth largest party - the new leader said it "was not good for Unionism" nor for this party.
But he added, as the crisis talks at Stormont continue, that the UUP must be ready for the next election, Westminster, Assembly or local government
"Who knows in the next few weeks we may be dusting down the posters and walking shoes again, but we must be able to channel the hurt and frustration we feel today into a positive energy that drives us forward and transfers into the strength and determination that will turn results around," he said.
On the talks process and whether the UUP would join a new Executive or go back to opposition, Robin Swann said he would not rule anything out.
He added: "If these talks end up being talks and agreements made by two parties for the benefit of two parties, then I say let it be an executive of two parties.
"Standing at the great height of 5”3ish, I have had my experiences of people trying to bully me and push me around… trust me – I have never been pushed around, nor do I intend starting to let people push me around, nor will I allow this party to be pushed around."
Mr Swann, who has served as an MLA for North Antrim since 2011, was officially endorsed at Saturday's meeting of the UUP ruling council.
He is the fourth leader of the UUP since David Trimble left the position in 2005.