Blondie had been on screen in a series of feature films with Penny Singleton (later of The Jetsons) in the title role, opposite Arthur Lake as Dagwood. In 1968, producers Joe Connolly and Bob Mosher (better known for Leave it to Beaver & The Munsters) adapted the long running comic strip into a sitcom, co-produced by Universal and King Features TV (KFTV's only live-action series that we know of), for CBS.
Patricia Harty was cast in the title role, with Will Hutchins (ex-Sugarfoot) as Dagwood. Jim Backus (ex-Gilligan's Island) was cast as Dag's boss, tyrannical Julius Dithers, and, to top it all off, child actors Peter Robbins & Pamelyn Ferdin, better known at the time for their work on the Peanuts specials (as Charlie Brown & Lucy, respectively) as Alexander & Cookie, though if memory serves, Alex & Cookie were already grown up in the strip by 1968.
Where CBS fouled up was airing the show on Thursdays. Back then, NBC owned the hour with Daniel Boone, which had a very loyal audience. The network might've been better served trying this on a different night.
I never saw the show, so I can't rate it. Gilmore Box uploaded the open.