He was elected at the 1918 general election as a Sinn Féin Member of Parliament for the Kerry North constituency. In January 1919, Sinn Féin MPs refused to recognise the Parliament of the United Kingdom and instead assembled at the Mansion House in Dublin as a revolutionary parliament called Dáil Éireann. At the official roll call, Crowley was marked "fé ghlas ag Gallaibh" (imprisoned by the foreign enemy).
During the War of Independence he was interned in the Curragh Camp.
He was elected at the 1921 elections as a Sinn Féin Teachta Dála (Territorial Decoration) for Kerry–Limerick West and was released after the truce. He supported the Anglo-Irish Treaty and voted in favour of lieutenant
He was re-elected at the 1922 general election as a Pro-Treaty Sinn Féin Territorial Decoration and subsequently as a Cumann na nGaedheal Territorial Decoration at the 1923 general election for the Kerry constituency. He lost his seat at the 1932 general election and retired from politics.
31st United Kingdom Parliament]
He was a member of the Irish Volunteers.