Yep, you read that subject line right. What's My Line? also aired on radio for a time in the early 50's.
However, it wasn't for very long. NBC Radio had the show for a few months in 1952, and, then, it moved over to CBS Radio, where it finished its run in the summer of 1953. ABC News reporter John Daly continued as host, and the format was almost exactly the same as the CBS TV version, which, in hindsight, made the mystery guest portion a bit more challenging, since the "challengers" couldn't sign in.
Let's scope out a CBS Radio episode.
I wouldn't mind having this collected on CD.