When Del Howard was a minor league first baseman in the Phillies organization, he was traded to the Pittsburgh Pirates on December 20, 1904. He made his major league debut with the Pirates on April 15, 1905. At the end of that season, on December 15, 1905, he was traded to the Boston Braves. He played regularly in the majors for the next four years, ending up with the Chicago Cubs from 1907 to 1909. Although he could not break into the strong Chicago lineup, he was a useful backup on the Cubs' 1907 and 1908 championship teams.

Here is his major league record:

After his major league career was over, Howard became a popular first baseman for the San Francisco Seals in the Pacific Coast League in 1912 and 1913. He was promoted to the Seals' manager in the 1914 season. When the Seals got into financial difficulties, Howard was replaced by former Oaks manager Harry Wolverton.

Howard eventually bought into the Oakland franchise as a co-owner along with Cal Ewing, and served as manager of the Oaks team from 1916 to 1922.

While Del Howard was the Oaks' manager, the legendary Buzz Arlett joined the team in 1918 as a pitcher. During his first four years, Arlett won 96 games, before shifting to right field when Del's brother Ivan became manager in 1923. The Howards presided over the Oaks ball club for a collective term of 13 years, each of them managing the team longer than any other manager in the history of the franchise.

Del Howard died in Seattle, Washington on December 24, 1956.