Wieghorst worked with the mounted patrol of the 7th Cavalry Regiment of the United States Cavalry (1920-1922) with occasional interludes as a wrangler on ranches in the western states. Wherever he went, he sketched and painted the Western culture he loved, often selling his work as calendar and magazine illustrations. His work appeared in Zane Grey's Western Magazine and Hoofs and Horns, an honor he shared with fellow cowboy artists including Daniel Cody Muller (1889–1976).^[3]

In 1924, Olaf Wieghorst married Brooklyn native Mabel Walters, In the same year, he joined the New York City Police Department (1924-1944) where he became a Mounted Police Officer with the Department. Due to his knowledge of horses, he was quickly sent to the Remount Section of the Mounted Unit where he broke and trained horses for the Unit. Wieghorst retired from the New York City Police Department in December, 1944, and once again headed west, with Mae and their son Roy. In 1945, Wieghorst settled in El Cajon, California, San Diego County, California and spent the rest of his life there working on his art. He was a self-trained artist and learned to work with oil painting and water colors himself. Over time he became a proficient painter and as a result, Grand Central Art Galleries chose to display his paintings. He also painted horses and studied their nature. The most famous of his models were Gene Autry’s Champion and Roy Rogers’ Trigger. ^[4]

He appeared in two John Wayne movies in the 60's; McLintock! (1963) and El Dorado (1966). Some of his art work was used in the open titles sequence in the film El Dorado (1966).^[5]

A retrospective of Wieghorst's work was presented at the National Cowboy and Western Heritage Museum (1974–75). In 1985 two of his works, The Navajo Madonna and The Navajo Man were sold for over $1 million. He died on April 28, 1988 in La Mesa, CA.^[6]