The Post Office Engineering Union (POEU) was a trade union in the United Kingdom. It represented engineering staff in the Post Office, mostly working in telecommunications.
The union was founded in 1915 when the Post Office Engineering and Stores Association and the Amalgamated Society of Telephone Employees merged, to form the Post Office Amalgamated Engineering and Stores Association. In 1922, following the establishment of the Irish Free State, the union's Irish section split away to form the Irish Post Office Engineering Union. In 1925, the Post Office Telegraph Mechanicians' Society joined the union. However, by 1939, membership was only 39,000.
By 1983, the POEU was the twentieth largest union in the UK, with membership around 130,000. In 1985, it merged with the Postal and Telecommunications Group of the Civil and Public Services Association, forming the National Communications Union.