Stewart was born in the Melbourne suburb of Footscray, Victoria and educated at Yarraville State School.

He was one of five original members of the VFU in the House of Representatives and took a large part in negotiating the formation of the Bruce–Page coalition government in late 1922, and he became Minister for Works and Railways in the resulting ministry.

As minister, he was also president of the River Murray Commission, which allowed him to press for the completion of the Hume Weir.

[1] In August 1924, Stewart resigned his portfolio in protest at a deal between Bruce and Page that protected sitting members from opposition from coalition party candidates at elections, which he regarded as an unwarranted restriction on voters' choice.

In September 1929, he voted against Bruce's bill to abolish the Commonwealth Court of Conciliation and Arbitration, helping to bring down his government.