John Farmer (c. 1570 – c. 1601) was a composer of the English Madrigal School. He was born in England around 1570 but his exact date of birth is not known - a 1926 article by Grattan Flood posits a date around 1564 to 1565 based on matriculation records. Farmer was under the patronage of Earl of Oxford and dedicated his collection of canons and his late madrigal volume to his patron. In 1595, Farmer was appointed Organist and Master of Children at Christ Church Cathedral, Dublin and also, at the same time, organist of St Patrick's Cathedral in Dublin. In 1599, he moved to London and published his only collection of four-part madrigals.

Giles Farnaby dedicated a pavan to him, included in the Fitzwilliam Virginal Book as Farmer's Paven (no. CCLXXXVII).