Barberton was a constituency in the Transvaal Province of South Africa, which existed from 1910 to 1958 and from 1974 to 1994. Named after the town of Barberton, it covered a part of the eastern Transvaal along the border with Eswatini. Throughout its existence it elected one member to the House of Assembly and one to the Transvaal Provincial Council.
When the Union of South Africa was formed in 1910, the electoral qualifications in use in each pre-existing colony were kept in place. In the Transvaal Colony, and its predecessor the South African Republic, the vote was restricted to white men, and as such, elections in the Transvaal Province were held on a whites-only franchise from the beginning. The franchise was also restricted by property and education qualifications until the 1933 general election, following the passage of the Women's Enfranchisement Act, 1930 and the Franchise Laws Amendment Act, 1931. From then on, the franchise was given to all white citizens aged 21 or over. Non-whites remained disenfranchised until the end of apartheid and the introduction of universal suffrage in 1994.
Like most of the rural Transvaal, Barberton had a largely Afrikaans-speaking electorate. In its first iteration, it was a marginal seat with a slight lean towards the South African Party, whose leader Jan Smuts was popular in the Transvaal. Its first MP, Joseph Petrus Jooste, resigned on election night, sparking South Africa's first (uncontested) by-election. Deneys Reitz, a protégé of Smuts, was first elected for Barberton in 1929 and served as a cabinet minister starting in 1935. He resigned in 1943 to take up appointment as High Commissioner in London, and in 1948, the seat was one of many in the Transvaal to fall to the Herenigde Nasionale Party. Its final MP, Wessel Hendrik Faurie, was elected for the new seat of Nelspruit on Barberton's abolition in 1958.
In 1974, Barberton was recreated to exist alongside Nelspruit, and by this time it was very safe for the governing party. Its only MP in its second iteration, Casper Uys, defected to Andries Treurnicht's Conservative Party on its formation in 1982, and was re-elected under this label in both 1987 and 1989.