The members of two teaching unions have voted to merge to form a new super-union, to be called the National Education Union (NEU).
The merged National Union of Teachers and the Association of Teachers and Lecturers will become the biggest union of teachers and educators in Europe.
ATL general secretary Mary Bousted said with nearly half a million members, the profession would have a stronger voice.
NUT head Kevin Courtney said the union would be a game-changer.
The NEU will be formed on 1 September and will represent some 450,000 teachers, as well as other education workers such as teaching assistants and support staff.
Members of the NUT and ATL were balloted between 27 February and 21 March.
ATL members’ response rate was 25% (29,841 votes), while the NUT’s was 23% (67,865 votes).
Of the ATL members who voted, 73% (21,722) said Yes to the merger, while 97% (65,908) of NUT members said Yes.
Ms Bousted said the merger was a “historic moment”.
“With nearly half a million members, we will speak with a stronger voice on behalf of education professionals and the children, young people and adults they support,” she said.
“The government will need to listen when we speak on the key issues facing education – funding cuts, excessive workloads, the recruitment and retention crisis, the chaotic exam reform and accountability.”
Mr Courtney said: “For too long, governments have played divide and rule amongst education unions. Today marks the beginning of the end of that.
“The NEU will be a game-changer in the education landscape and I am delighted to be jointly leading it forward over the coming months and years.”
Ms Bousted and Mr Courtney plan on sharing the post of general secretary, saying they have a good working relationship and jointly can “get our union in many more places”.
Prof Howard Stevenson, director of research at Nottingham University’s School of Education, said the union amalgamation was a “development of international significance”.
“Experience of amalgamations and mergers is quite limited and often small scale. When the two huge teacher unions in the USA sought to merge, this development was rejected in a ballot,” said Prof Stevenson.
“The amalgamation of NUT and ATL is on a scale that has not been seen previously, and may be the beginning of a trend, as teachers everywhere face common pressures.
“There is no easy evidence that fewer, bigger unions necessarily generate better outcomes for teachers. There is however considerable evidence that employers and governments deliberately seek to exploit divisions.
“Making this more difficult will make it harder for government to impose change without wider support and may presage the need for a new relationship between government and teacher unions.”