Taoiseach Leo Varadkar said it was a "significant day" for Ireland.
"We have achieved all that we set out to achieve in phase one of these negotiations," he told a press conference in Government Buildings in Dublin.
"I am satisfied that sufficient progress has now been made on Irish issues, the parameters have now been set and they are good."
He said Ireland's focus would now move to phase two of the negotiations. Mr Varadkar said his government would remain "fully engaged and vigilant" throughout the process.
"This is not the end but it is the end of the beginning," he said.
Mr Varadkar said he wanted to assure unionists of his motivations.
"There is no question of us trying to exploit Brexit to move toward Irish unity without consent," he said.
'The Good Friday Agreement in all of its parts, has been protected' says Leo Varadkar, Irish Prime Minister on Brexit deal pic.twitter.com/xjj60iLn4L
— Sky News (@SkyNews) December 8, 2017
'Today is a very significant day... we have reached a satisfactory conclusion' says Leo Varadkar, Irish Prime Minister following progress in Brexit negotiations pic.twitter.com/sEPdWvv5RR
— Sky News (@SkyNews) December 8, 2017