| Program | Episode | Date | Notes |
| California Melodies | Karloff appeared with the Hallelujah Quartet | Jan. 3, 1932 | |
| Hollywood on the Air (Hollywood on Parade) | Karloff appeared with Katharine Hepburn | Nov. 25, 1932 | |
| Hollywood on the Air (Hollywood on Parade) | Karloff appeared with Victor McLaglen | Oct. 7, 1933 | |
| California Melodies | Karloff appeared as a guest | Oct. 24, 1933 | |
| Hollywood on the Air | Karloff appeared as a guest | Jan. 27, 1934 | |
| Forty-Five Minutes in Hollywood | Karloff appeared as a guest twice | Feb. 15 & Aug. 2, 1934 | |
| The Show | Episode "Death Takes a Holiday" | Aug. 27, 1934 | |
| The Fleischmann's Yeast Hour (with Rudy Vallee) | Episode "Death Takes a Holiday" | Oct. 11, 1934 | |
| Shell Chateau (hosted by Al Jolson) | Episode "The Green Goddess" with George Jessel | Aug. 31, 1935 | |
| Hollywood Boulevardier | interviewed by Ben Alexander | Dec. 30, 1935 | |
| The Fleischmann's Yeast Hour (with Rudy Vallee) | Episode "The Bells" | Feb. 6, 1936 | |
| In Town Tonight | Karloff appeared as a guest | Feb. 22, 1936 | |
| The Fleischmann's Yeast Hour (with Rudy Vallee) | Karloff appeared as a guest | Sept. 3, 1936 | |
| Camel Caravan | Episode "Death Takes a Holiday" with Benny Goodman | Dec. 8, 1936 | |
| Concert Orchestra | Karloff appeared with Dolores Del Rio | Sept. 2, 1936 | |
| The Royal Gelatin Hour (aka Vallee's Varieties) | Karloff reads "Resurrection"; co-starred Tom Mix | Nov. 11, 1937 | |
| The Chase and Sanborn Hour (aka The Charlie McCarthy Show) | Recites "The Evil Eye" ("The Tell-Tale Heart") | January 30, 1938 | |
| The Baker's Broadcast | Karloff and Bela Lugosi sang a duet on this show called "We're Horrible, Horrible Men"; co-starring Ozzie and Harriet | Mar. 13, 1938 | |
| Lights Out | Episode: "The Dream" | 23 March 1938 | |
| Lights Out | Episode: "Valse Triste" | 30 March 1938 | |
| Lights Out | "Cat Wife" by Arch Oboler | 6 April 1938 | |
| Lights Out | Episode: "Three Matches" | 13 April 1938 | |
| Lights Out | Episode: "Night on the Mountain" | 20 April 1938 | |
| The Royal Gelatin Hour (hosted by Rudy Vallee) | Skit "Danse Macabre" | May 5, 1938 | |
| Hollywood (hosted by George McCall) | appeared as a guest | Oct. 27, 1938 | |
| The Eddie Cantor Show | Variety show | Jan. 16, 1939 | |
| The Royal Gelatin Hour (with Rudy Vallee) | Skit "Resurrection" | April 6, 1939 | |
| Kay Kayser's Kollege of Musical Knowledge | appeared with Bela Lugosi and Peter Lorre promoting their film You'll Find Out | Sept. 25, 1940 | |
| Everyman's Theater | Episode "Cat Wife" by Arch Oboler | Oct. 18, 1940 | |
| Stars on Parade | Episode "The Big Man" | 1941 | |
| Information Please | Radio Quiz show | Jan. 24, 1941 | |
| ASCAP on Parade | appeared as a guest | Feb. 8, 1941 | |
| Best Plays | Arsenic and Old Lace | 1941 | |
| Kate Smith Variety | appeared as a guest | March 7, 1941 | |
| Hollywood News Girl | Karloff interviewed | Mar. 22, 1941 | |
| Inner Sanctum | Karloff acted in 21 episodes of this radio show | Mar. 16, 1941 – July 13, 1952 | (See subsection on Karloff's "Inner Sanctum" radio appearances below.) |
| We the People | appeared as a guest | Apr. 1, 1941 | |
| The Voice of Broadway | Karloff interviewed | Apr. 19, 1941 | |
| WHN Bundles for Britain | appeared as a guest | June 14, 1941 | |
| United Press is on the Air | appeared as a guest | July 11, 1941 | |
| The Gloria Whitney Show | appeared as a guest | Aug. 13, 1941 | |
| The USO Program | appeared with Paul Lukas | Nov. 23, 1941 | |
| Time to Smile | hosted by Eddie Cantor | Dec. 7, 1941 | |
| Keep 'em Rolling | Episode "In the Fog" | Feb. 8, 1942 | |
| Information Please | Karloff appeared on this quiz show with John Carradine | Feb. 20, 1942 | |
| Information Please | TV Quiz Show | May 17, 1943 | |
| Blue Ribbon Town | hosted by Groucho Marx | July 24, 1943 | |
| The Theatre Guild on the Air | Arsenic and Old Lace | 1943 | |
| Creeps By Night | 30-minute suspense anthology; Karloff starred in ten episodes | Feb. 15-May 9, 1944 | (See subsection on Karloff's "Creeps by Night" radio appearances below.) |