From his debut on 5th February 1922 singing into a broadcasting wireless telephone at the Westinghouse plant in Newark reaching most of the eastern US to his final major broadcast on 22nd May 1950 for the Lux Radio Theatre's version of Jolson Sings Again, Al Jolson was a big star of radio.
In his book The Legend Comes To Life Herbert Goldman lists 372 broadcasts of which 308 were starring series and 64 were guest appearances.
Counting his two stints as host of the Kraft Music Hall (1933-1934 and 1947-1949) separately Jolson had six starring series on radio as follows :
Presenting Al Jolson (Chevrolet, General Motors) (1932-1933) (15 shows)
Kraft Music Hall (1933-1934) (26 shows)
Shell Chateau (1935-1936) (39 shows)
Cafe Trocadero/ Lifebuoy (1936-1939) (99 shows)
Al Jolson (Colgate) (1942-1943) (39 shows)
Kraft Music Hall (1947-1949) (71 shows)
You can hear some of Al's classic radio shows here on a 24/7 Radio Station.