In 1918 various New South Wales teachers' associations such as the NSW Public School Teachers' Association, the NSW Public School Assistant Teachers' Association, the Women Teachers' Association, the Headmasters' Association, the Manual Training Teachers' Association and the Sewing Mistresses' Association, met to discuss the likelihood of an amalgamation. The result was the founding of the New South Wales Teachers' Federation in 1919. Without rivals it gained and held the loyalty of most teachers throughout the 1920s. Despite a lull in membership during the Great Depression years, the NSW Teachers' Federation formally linked itself to the state and national trade union movement during World War Two by affiliating with the NSW Labour Council and the Australian Council of Trade Unions. After the war large salary gains were achieved and about 90% of teachers became members of the union. The New South Wales Teachers' Federation was instrumental in lobbying the government of the day to introduce equal pay for women in 1958 and 1963. The NSW Teachers' Federation is affiliated with the Australian Education Union, constituting its NSW Branch whilst retaining its separate identity.

In October 2015 the union changed its name from The New South Wales Teachers Federation to the Australian Education Union New South Wales Teachers Federation Branch.