Around May 1940 Gertrude was heard Monday through Fridays over NBC on Light of the World (NBC) a Biblical series transplanting the Bible into modern prose on June 29. 1940 she was heard in "The Twenty-First Girl" an episode of Listeners Playhouse (NBC).

Warner's first real starring role on radio came when she was 23, switching to CBS, she played Rebecca Lane, in Beyond These Valleys (CBS, Aug 1940) it featured her as a young girl who yearns for happiness beyond the valleys of the small Iowa in which she lives. Santos Ortega also appeared on this show.

By 1944 she'd been noticed and selected for both lead and co-starring support roles in a wide array of straight dramas and mystery or detective dramas. An article from 1944 claims Gertrude's year income was nearly $100,000. Following the success of her co-starring appearances with Victor Jory in Dangerously Yours aka Matinee Theatre (CBS, 1944 - 1945), and (again) appearing opposite Santos Ortega in (The New Adventures of) Perry Mason (CBS, 1943 - 1945). For Matinee Theater's "Dark Victory" (CBS, Feb 5. 1945), the dramatic success of stage and screen she was heard on radio, with the same Victor Jory (in the role of Dr. Fred Steele). Gertrude Warner played the Park avenue girl who learned that she is going blind.

In the serial This Life is Mine (CBS, April 18. 1945), a new story sequence began, Gertrude Warner and Michael Fitzmaurice continued as leads. In 1946 Gertrude who played the role of Eden Channing was temporarily replaced by Julie Stevens.

She was picked up as the co-star in The Adventures of Ellery Queen (CBS, beginning Jul 25. 1945). She was also still appearing in Theatre of Romance (CBS), Brownstone Theatre (Mutual, beginning Feb 21. 1945), The Mysterious Traveler (Mutual, 1945) and several daytime soap operas of the era.

The Mercury Theatre on the Air who produced live radio dramas briefly reappeared in 1946 and Trudy appeared in "Jane Eyre" (CBS, Jun 28. 1946), the classic of English letters. Once again with Victor Jory, with whom she had previously performed the play for Matinee Theatre (CBS, Dec 3. 1944)

Trudy Warner was first married around May 1946, prompting a voluntary suspension of her radio career and her departure from the successful Ellery Queen Mystery program. Nikki was written out of the script until the middle of July when Charlotte Keane took over. Around this time rumors were going around another Ellery Queen series would be filmed with Gertrude Warner, "The Nicky of the Air Waves", starring. This never came to pass.

Apparently, the retirement/suspension was short-lived since as soon as 1947 she appeared in yet another array of daytime dramas, regular adventure series, and specials. This was the case in Studio One (CBS, 1947-1948) the anthology series, created in 1947 by the 26-year-old Canadian director Fletcher Markle. She also joined the cast of NBC's daytime serial Backstage Wife, in the role of Albertine (Oct 1947) and in December 1947 she was in Sherlock Holmes mystery series (Mutual).

Sponsored by Proctor and Gamble, Joyce Jordan, M.D. was a radio soap opera that was broadcast from 1944 daily in 15-minute episodes. Starring Trudy Warner (NBC, 1947-48), the program was about a young woman doctor and her interactions with her patients and other people in her work and personal life. Prone to daydreaming, Joyce’s thoughts were heard throughout the program.  

From his very first broadcast in 1936, the banker-hero of New England, David Harum, became an on-the-air crusader "for love ... for happiness ... and the good way of life." Never married, he resided in the home of his sister, Polly Benson (called Aunt Polly on the show) and her husband, James, who operated the local hotel. This 15 minutes serial at one point (CBS, 1948 - 1949) featured Gertrude Warner as Susan Wells opposite Cameron Prud'homme (David), Charme Allen (Aunt Polly) and Kenneth Williams (Brian Wells).

Jay Jostyn brought his radio experience to the "Marriage for the Millions" program. In this seventh (Feb 1949) of the series, Mr. Jostyn as Ben Green discusses his problems with a family agency caseworker played by Gertrude Warner.

Hosted by John Dickson Carr, Gertrude played in Murder by Experts 'The Dark Island" (Mutual, Aug 8. 1949) where a woman marries a writer when he rents a cottage on a lonely island owned by her father. Is he really, "The Scalpel Killer?".

Opposite John Garfield she played Belle Mercer in "The Prizefighter and the Lady" in The MGM Theater of the Air (Syndication, Nov 11. 1949)

She was also appearing in several Cavalcade of Americas (NBC, 1949 - 1952), as well as the now routine number of concurrent daytime soap operas.

In Sep 1949 she appeared as Margot Lane [7th] in The Shadow (Mutual), with Brett Morrison. Gertrude often contended that she was hired for her ability to scream. She held that role for more than 5 years until 1954. Sadly, because many of the Shadow’s adventures were being recorded on magnetic tape at that time and then erased to use the tape over and over again, not many of Warner’s broadcasts ("The Vengeance of Angela Nolan - June 27. 1954") remain for new generations to hear.

Her off-the-air-waves activities include hospital tours for the Theatre Wing as well as courses in art and singing.

Gertrude won the role of Teresa Blake in the serial Just Plain Bill (NBC, Nov 1950). 

Learning about the lives of great Americans can be hugely entertaining as well as educational. The NBC anthology program American Portraits made the most of this during the programs lengthy run. "A Storm At Monticello" featured Gertrude (NBC, July 17. 1951) and the same year Dimension X (NBC, July 19. 1951) featured stories that were literally “out-of-this-world," had her going to Mars.

Because radio kept the actress busy, Trudy expressed little to no interest in silver or small screen work save for television commercials and a brief appearance as Claire English in TV's As the World Turns (CBS, January 1960 to September 1960).

Returning to radio in one of the longest-running detective series Yours Truly Johnny Dollar (CBS, 1961), Suspense (CBS, 1962) and Theater Five (ABC, 1964-65) a radio series whose title was derived from the fact that it was aired everyday at 5pm. Hosted by Fred Foy it was ABC’s attempt to revive radio drama, so everything in the show was top notch.

As radio faded, she became an instructor at Weist-Barton School of Television and Commercial Acting in New York and at Oberlin College in Ohio.

Gertrude Warner died in New York City on January 26. 1986 from cancer. Her successful radio career continued for 28 years and well over 4,000 performances. She was considered one of the queens of daytime radio.