The UK government has been urged to implement a "meaningful, comprehensive and transparent process" for the devolved administrations to influence Brexit talks.
A joint statement aimed at Downing Street was issued following a meeting in London.
It was attended by Northern Ireland's First Minister Arlene Foster and her deputy Michelle O'Neill, as well as ministers from Scotland and Wales.
They said they had not been given the role they hoped for in the first round of talks.
With the next round of discussions with the European Union taking place next week, the devolved administrations called on Westminster to listen to the needs and interests of Northern Ireland, Scotland and Wales.
The statement said: "Before the next round of negotiations later this month we agreed there must be a meaningful, comprehensive and transparent process for the devolved governments to influence the UK's negotiating position - something that has clearly not happened so far.
"These negotiations will have significant and long-lasting impacts on people, communities and businesses and the devolved governments have a particular responsibility for ensuring the interests of Scotland, Wales and Northern Ireland are protected and promoted.
"Each of our governments have particular concerns and these must be taken seriously with the opportunity to directly influence the UK negotiating position."
It added: "With the next round of negotiations just eight days away there is an urgent need for meaningful and constructive engagement by the UK government at all levels on this issue - with proper opportunities to help decide the UK's position in the most significant negotiations in decades."
The UK officially left the EU on 31 January and now has until 31 December to finalise the future relationship with the bloc.
The statement represents the second time this year the devolved legislatures have voiced their discontent in unison at the Brexit process after all three rejected a legislative consent motion (LCM) for British Prime Minister Boris Johnson's exit deal.
An LCM, however, is not binding - meaning the UK Government was able to continue with its deal and leave the EU on 31 January.