The name Ghana National Association of Teachers appeared in the history of Trade Unionism in Ghana in 1962. This however does not mean there were no teacher organizations operating in the country before that time. There were Teacher Associations, based on place of work and employer, such as the church educational units, government school teachers and local government teacher organizations.

The origins of the Ghana National Association of Teachers is traced to the 1930s when as a result of the World War 1, economies of many countries, including that of the Gold Coast (Ghana) suffered a great decline. In 1931, there was a trade slump and prices of commodities fell. Cocoa, which was the mainstay of the Gold Coast economy, suffered severely. To contain the situation, the Colonial Government decided to introduce some austerity measures by making cuts in public spending, as a means of reducing its total financial burden. The axe fell heavily and unexpectedly on education.

The colonial government decided to reduce the salaries of mission school teachers who were already discriminated against in terms of physical infrastructure, salaries and other conditions of service, as compared to the Government school teachers who were regarded as part of the colonial administration. In fact, a committee appointed by the government and chaired by Mr. F.E. Tallard to consider the cost of education to government and recommend a means to reduce it by 50,000 pounds, recommended that the non-government school teachers' salaries should be reduced by 29%.

The non-government school teachers under the leadership of  Mr.  J.T.N Yankah protested against this injustice vehemently and submitted a petition signed by 8000 teachers from the Eastern part of the country to the colonial government. Mr. E. Y Anipare, a teacher under Yankah was very instrumental in the collection of the signatures. In addition to the petition, the group lobbied the African members of the legislative council to support their petition. At the end of the day, the petition was carried and the 29% salary reduction directed against the mission school teachers was dropped and a general 5% salary cut slapped on all workers on the central government's payroll, but was later withdrawn, altogether.

The protest and its outcome jolted the teachers to the realization that there was strength in unity. Subsequently, the Mission School Teachers came together to form the Assisted School Teachers Union (ASTU) in 1931, to protect their interests. In the attempt to embrace all teachers in the country, the union changed its name  to the Gold Coast Teachers Union (GCTU) in 1937. Between 1931 and 1958, two rival unions operated in the country. They were the Gold Coast Teachers Union and the National Union of Teachers (NUT).

However through the influence of the ruling Convention People's Party (CPP) government and the Industrial Relations Act, 1958, the two unions were brought together in a merger, under the Trades Union Congress (TUC), as the Teachers and Cultural Services Union. The teachers were unhappy under the TUC because:

(i) Not all teachers could become members of the TUC as those on salaries of £680 and above per annum could not unionize; and

(ii) They felt they were professionals. Teachers therefore started agitating and in 1962, the government directed that they opt out of the TUC.

The new union, the Ghana National Association of Teachers was inaugurated on 14th July 1962, by the Minister of Education of the time. For about thirteen years (1962 - 1975), the Association was organized along the lines of constituent bodies, prominent among them, the Elementary School Teachers Association (ESTA), the Association of Secondary School Teachers (ASST), the Association of Teachers of Training Colleges (ATTC), the Association of Teachers of Technical Institutions (ATTI) and the Association of Teachers in Education Units. In 1975, at Achimota, all the constituent bodies were abolished and the GNAT started operating as a unified body of teachers in all pre-tertiary educational institutions and offices. The Ghana National Association of Teachers is a non-partisan, non-sectarian, equal-opportunity professional Association of Teachers in pre-tertiary education institutions and offices in Ghana.

The Association was registered under the Trustee Incorporation Act of 1962 and recognized by the Ghana Education Service Act, 1995 (Act 506) (section 16) as the only body which represented teachers in Ghana. Currently, the Ghana National Association of Teachers is registered as a trade union, under the Labour Act, 2003 (Act 651), and holds the Collective Bargaining Certificate, on behalf of all teachers in the GES.