Famous for his late nineteenth-century architectural works, Irwin designed such Indian landmarks as the Madras High Court in Chennai and the Amba Vilas Palace in Mysore.
In the mid-1880s, he was hired by British India's Public Works Department.
He was a key architect of the late 19th-century Indo-Saracenic movement.
A native of Ireland, he later settled in British-controlled India. His marriage to Henrietta Helen Irwin resulted in sons named Harloe and Henry and in twin daughters named Henrietta and Helen.
He and Charles Correa both made significant contributions to Indian architecture.