John Trefusis (c. 1586 – 1647) lord of the manor of Trefusis in the parish of Mylor in Cornwall, was an English politician who sat in the House of Commons from 1621 to 1622.
Trefusis was the eldest son and heir of John Trefusis (d.1603) of Trefusis by his wife Mary Gaverigan, a daughter and co-heiress of Walter Gaverigan of Gaverigan, Cornwall.
[3] He matriculated at Broadgates Hall, Oxford on 3 May 1605 aged 18 and was a student of law at the Inner Temple in 1607.
He succeeded his father in 1603, inheriting several manors.
In 1621 Trefusis he was elected Member of Parliament for Truro in Cornwall.