In 1895, he moved to Cleveland, Ohio, where he went to work as a sewing machine repair man for a manufacturing company. Garrett had a knack for fixing things. This word traveled fast, which led to him receiving numerous job offers from various manufacturing companies in Cleveland.

In 1907, he opened his own sewing and repair shop. In 1909, he expanded to include a tailor shop. In 1920, he entered the newspaper industry, establishing the "Cleveland Call". Garrett became very prosperous and a well-respected business man.

After witnessing an accident between an automobile and an animal-powered wagon, he decided to experiment with traffic light signals.

He invented a t-shaped pole which featured three positions: stop, go and all-directional stop. His patent was granted November 20, 1923, which was later patented in Great Britain and Canada.

He later sold the rights to the traffic light signal to General Electric Corporation. Before his death in 1963, he was awarded a citation for his traffic signal by the US Government.