The Garda Representative Association has overwhelmingly rejected the Lansdowne Road Agreement.
Of the 10,000 members, 86.5% voted no while 10.9% voted yes. The remainder of votes were spoilt.
The turnout was 60%.
The GRA Executive - which had not issued a recommendation for or against acceptance - will hold a special meeting next Tuesday to discuss the outcome.
The Association of Garda Sergeants and Inspectors, which represents around 2,000 mid-ranking gardaí, rejected the public service pay deal by 52.6% to 47.4%.
Its leadership had issued no recommendation on the deal.
It is understood that many gardaí object to the additional 30 hours unpaid overtime a year which they had to undertake under the Haddington Road Agreement - and are also frustrated at the delay in a review of industrial relations processes affecting them.
The LRA has already been accepted by a majority of unions affiliated to the Irish Congress of Trade Unions.
Three affiliated unions - the Irish Medical Organisation, Unite and the Association of Higher Civil and Public Servants - have rejected the LRA, but accepted the majority Congress vote.
However, the Teachers Union of Ireland and the Association of Secondary Teachers in Ireland have also rejected the deal, but have said they will not be bound by the majority outcome.
Neither the AGSI nor the GRA are affiliated to ICTU so the question of accepting the majority verdict does not arise.
It's expected that despite voting no, the teachers and gardaí will receive the benefits of LRA pay restoration through the reduction of the pension levy.
However, recent legislation permits the Government to withhold increments and certain special payments from workers that are not signed up to a collective agreement.