The Farrely surname comes from the Irish Gaelic name Ó Fearghail, which means "a valiant warrior." Early Origins of the Farrely family The surname Farrely was first found in Leinster, where they were found mainly in County Longford. Feargal, Prince of Annaly appears number 105 on the "Line of Ir" descendants.

Farrelly is a surname of Irish origin. It is derived from the Gaelic name Ó Fearghaile, which means "descendant of Fearghal." The name Fearghal itself is composed of two elements: "fear," meaning man, and "gal," meaning valor. Therefore, the name Farrelly can be interpreted as "descendant of the man of valor."

Farrelly is an anglicised form of Ó Faircheallaigh, a family name of the Irish nobility from County Cavan. The patronym means "descendant of Faircheallaigh", whose name means "super war". Faircheallaigh was the son of Ailill, a 7th-great-grandson of Niall, King of Ireland.