Harrison became production manager for All-American Publications in 1942. When All-American became part of National Comics (later known as DC Comics), Harrison continued to work for the newly merged publisher. He was the colorist for the company's covers for 15 years. In 1972, he suggested publishing comics in an oversized format stating that "We could create a tabloid size comic that would stand out on the newsstand." This led to the launch of the Limited Collectors' Edition series later that year. He developed an internship program at DC which was later nicknamed the "Junior Woodchucks" by Bob Rozakis. In 1973, Harrison became DC's Vice-President in Charge of Operations and developed the idea of the DC Comicmobile, a van which sold comic books "like the ice cream man did". Harrison and Adler were featured on the cover of DC's self-produced fan magazine The Amazing World of DC Comics #10 (Jan. 1976). Harrison was promoted to president of the company in 1976 just as Jenette Kahn became publisher. Kahn stated in a 2012 interview that "I can't really say that Sol and I had much of a working relationship. He, more than anybody, resented my being hired because he felt that the job was rightfully his." Harrison served as president of the Comics Magazine Association of America from 1979 to 1980. He retired from DC Comics at the end of February 1981 and moved to Florida.
In 1985, Harrison was named as one of the honorees by DC Comics in the company's 50th anniversary publication Fifty Who Made DC Great.
^Rozakis, Bob (October 17, 2011). "A Day at the New York Comic-Con". Anything Goes. Archived from the original on July 15, 2013. Retrieved 2013. Back in the very early days of our careers at DC Comics, then VP/Production Manager Sol Harrison decided that we "kids" should put together a company-backed fanzine called Amazing World of DC Comics. He came to my desk and said, "Go get the rest of your pals and bring them to my office." So I went to my compatriots and said, "Sol wants to have a Junior Woodchucks meeting." I was making a joke, using the name of the faux-Boy Scouts that Huey, Dewey and Louie of Donald Duck fame belonged to.
^Hamlin, Brad (August 2011). "Mystery Island Interviews DC Comics Super Alumni Bob Rozakis". Archived from the original on March 27, 2012. Retrieved 2012. The Comicmobile was the brainchild of Sol Harrison, who was the VP at DC at the time. He thought that a good way to sell comics would be to have a fleet of vans that drove up and down the streets like the ice cream man did.
^Levitz "The Bronze Age 1970-1984" p. 452: "Replacing [Carmine] Infantino in 1976 was a balance of experience and the improbable: 55-year-old production exec Sol Harrison, who had worked on National's very first comics as a color separator before being moved up to president. He was teamed with an unlikely equal partner as publisher, a 28-year-old woman from outside comics, Jenette Kahn."
^Greenberger, Robert (July 2012). "The Path of Kahn". Back Issue!. Raleigh, North Carolina: TwoMorrows Publishing (57): 12.