Smith was elected as the Australian Labor Party member for the Australian House of Representatives seat of Denison at the 1910 election.
 In December 1915, he married Mabel Ellen Russell—they had no children.
 He was an Assistant Minister during the Second Hughes Ministry from 14 November 1916 to 17 February 1917.
 He was a strong supporter of Prime Minister Billy Hughes and campaigned for conscription at the October 1916 plebiscite.
 Smith left the Labor Party with Hughes in the 1916 Labor split and joined the Nationalist Party when it was established.

In the Fifth Hughes Ministry he was an Honorary Minister from 4 February 1920 until he was made Minister for the Navy on 28 July 1920.
 He was Minister for the Navy until 21 December 1921.
Owing to the end of the war, he was obliged to carry out a significant reduction in the capacity of the Royal Australian Navy.
The position of naval minister was abolished in December 1921, with responsibilities transferred to the Minister for Defence, and Smith was not reappointed to the ministry.
At the 1922 election, he was opposed by Labor and two other independent Nationalist candidates, losing to Labor's David O'Keefe.
Smith was elected as the Australian Labor Party member for the Australian House of Representatives seat of Denison at the 1910 election.  In December 1915, he married Mabel Ellen Russell—they had no children.  He was an Assistant Minister during the Second Hughes Ministry from 14 November 1916 to 17 February 1917.  He was a strong supporter of Prime Minister Billy Hughes and campaigned for conscription at the October 1916 plebiscite.  Smith left the Labor Party with Hughes in the 1916 Labor split and joined the Nationalist Party when it was established.
In the Fifth Hughes Ministry he was an Honorary Minister from 4 February 1920 until he was made Minister for the Navy on 28 July 1920.  He was Minister for the Navy until 21 December 1921. Owing to the end of the war, he was obliged to carry out a significant reduction in the capacity of the Royal Australian Navy. The position of naval minister was abolished in December 1921, with responsibilities transferred to the Minister for Defence, and Smith was not reappointed to the ministry. At the 1922 election, he was opposed by Labor and two other independent Nationalist candidates, losing to Labor's David O'Keefe.
William Laird Smith