Tierney came to corporatism through a study of Catholic social thought, and through an analysis of continental systems of corporatism, particularly those of Portugal and Austria. He was an early member of the Army Comrades Association (later known as the Blueshirts) and, along with Ernest Blythe, encouraged Eoin O'Duffy to become the leader. Tierney suggested the name "Fine Gael" for the new coalition between his party, the Centre Party and the Blueshirts.
He was the prime mover behind the transfer of UCD to its present site at Belfield. He married Eibhlín MacNeill, daughter of Eoin MacNeill, and wrote a biography of his father-in-law, Eoin MacNeill: scholar and man of action (1980).