Public sector members of the Unite trade union have rejected the Haddington Road Agreement by 72.6% to 27.4%.
Following a meeting at the end of May, the union had recommended that its 6,000 public service members reject the agreement on pay and conditions.
Unite's Regional Secretary Jimmy Kelly said the Haddington Road proposals were bad for the public sector as they would take €1bn out of the sector and would lead to job losses.
Speaking to RTÉ's Morning Ireland, he also criticised the Government for what he claimed was interference with the union's freedom to have a ballot on the proposals.
"The freedom to have a ballot has been interfered with by the Government from day one.
"The threat to punish people who vote against Haddington Road proposals is a disgrace and all unions should be against what's been denied in terms of free collective bargaining and the right of our members to reject these plans," he said.
Mr Kelly said Unite would wait to see whether other unions would accept or reject the proposals before fully deciding on its next course of action.
A meeting of Unite public sector representatives will be held later to consider the result and discuss further steps.