At the 1931 general election, Thorby won the federal  seat of Calare, which he held until 1940. He was a Minister without Portfolio from November 1934 to November 1937 in the Lyons government, entitled Assistant Minister for Repatriation (1934–35), Minister for War Service Homes (1935–36) and Assistant Minister for Commerce (1935–37).
From 1931 to 1940, Thorby represented the Calare federal seat. He held various ministerial positions in the Lyons government from 1934 to 1937, including Assistant Minister for Repatriation, Minister for War Service Homes, and Assistant Minister for Commerce.