Finishing his education at the age of 30, he sold insurance for a year before joining North Toronto Collegiate Institute as a history teacher.

After seven years, he moved to Vaughan Road Collegiate Institute in the suburb of York, Toronto becoming head of the English department.

Noseworthy became the President of the Ontario Secondary School Teachers' Federation in 1938 serving a one year term.

It was tradition for the Liberals and Conservatives not to run against the other party's leader in by-elections, but the CCF did not accept this convention.

The result on February 9, 1942, was a major upset and breakthrough for the CCF, with Noseworthy being elected by a margin of 5,000 votes.