In 1894, Pilkington emigrated to Western Australia. He practiced law initially at York in 1895, and then at Perth. He returned to Ireland in 1899, marrying Ethel Longworth-Dames there on 13 December; they had one daughter before her death in 1920. After returning to Perth, Pilkington was made a King's Counsel in 1906, and practiced in partnership with Walter James from 1907.
On 22 July 1917, Pilkington was elected to the Legislative Assembly seat of Perth in a by-election occasioned by the resignation of James Connolly, who had been appointed Agent-General for Western Australia in London. He held the seat until the election of 12 March 1921, when he did not contest the seat. Victor Courtney somewhat uncharitably described him as "a tall, austere, aloof English lawyer... quite out of touch with public opinion... He was a dyed-in-the-wool conservative and did not care who knew. I name him as the giver of the most tactless answer to a questioner I have ever heard".