Within four years, he was promoted to the position of general superintendent of the Western Electric Light Company of Chicago, Illinois.

The following year, he established Leonard and Izard, a firm that set up electric railways and generating stations.

In 1898, he left the Edison organization and incorporated his own Ward Leonard Electric Company on February 19, 1898, in the village of Bronxville in Westchester County, New York.

In a Ward Leonard system, a prime mover drives a direct current (DC) generator at a constant speed.

From the 1920s through the 1980s most electrically driven elevators used Ward Leonard control and many systems remained in use at the beginning of the 21st century.

H. Ward Leonard was an active member of the American Institute of Electrical Engineers, publishing technical papers, attending meetings and making presentations.

He died suddenly on February 18, 1915, in New York while attending the annual dinner of the American Institute of Electrical Engineers.