County Mayo (UK Parliament constituency)

Mayo
Former County constituency for the House of Commons
1801–1885
Number of members	Two
Replaced by	East Mayo, North Mayo, South Mayo and West Mayo

Mayo was a parliamentary constituency in Ireland, which returned two Members of Parliament (MPs) to the House of Commons of the Parliament of the United Kingdom from 1801 to 1885.

The constituency was created at the Act of Union 1800, replacing the earlier Mayo constituency in the pre-union Parliament of Ireland. Under the Redistribution of Seats Act 1885 it was divided into four new single-seat constituencies: see East Mayo, North Mayo, South Mayo and West Mayo.

This constituency comprised the whole of County Mayo.

The elections in this constituency took place using the first past the post electoral system.