Theresa May has hailed the EU draft agreement on post-Brexit relations as "right for the whole of the UK", in a brief statement in Downing Street.
The political declaration - outlining how trade, security and other issues will work - has been "agreed in principle", the European Council says.
London and Brussels have already agreed the draft terms of the UK's exit from the EU on 29 March 2019.
The prime minister will make a statement to MPs at 15:00 GMT.
Mrs May, who has briefed her cabinet on the agreement in a conference call, said the agreement "delivers on the vote of the referendum".
"The British people want this to be settled. They want a good deal that sets us on course for a brighter future. That deal is within our grasp and I am determined to deliver it," she added.
Last week, the UK and the EU agreed a 585-page legally-binding withdrawal agreement, covering the UK's £39bn "divorce bill", citizens' rights after Brexit and the thorny issue of the Northern Ireland "backstop" - how to avoid the need for a manned border on the island of Ireland.
The political declaration is a separate, far shorter document, setting out broad aspirations for the kind of relationship the UK and the EU will have after Brexit, and is not legally-binding. Some of the wording of it is non-committal and allows both sides to keep their options open.
Source: bbc