The 1899 Oldham by-election occurred in the summer of that year, and involved a by-election to fill both seats in the two-member Oldham Parliamentary borough. The block voting method allowed each elector to vote for two candidates.

Oldham was a parliamentary constituency centred on the town of Oldham, England. It returned two Members of Parliament (MPs) to the House of Commons of the Parliament of the United Kingdom. The constituency was created by the Great Reform Act of 1832 and was abolished for the 1950 general election when it was split into the Oldham East and Oldham West constituencies.