He was first elected to represent Knocktopher in the Irish House of Commons in May 1761, and sat until he resigned his seat in March 1800.
His views are said to have been influenced by his lifelong friendship with Edmund Burke, who wrote an open "Letter to Sir H. Langrishe" in 1792, encouraging his efforts to secure relief for Catholics from the rigours of the Penal Laws.
On 19 February 1777 he was created a Baronet, of Knocktopher, County Kilkenny, in the Baronetage of Ireland.
The elder son Robert succeeded as second baronet, and died in 1835, having sat in the Irish parliament as M.P.
The second son James was archdeacon of Glendalough, dean of Achonry, and rector of Newcastle Lyons, and Killishin, County Carlow.