Allen and Dorothy Goodman married in 1943 and had three children — Steve Jr., Brian, and David. That marriage ended in divorce in 1952.

Allen became an announcer for radio KFAC in Los Angeles, then moved to the Mutual Broadcasting System in 1946, talking the station into airing his five-nights-a-week comedy show Smile Time, co-starring Wendell Noble. After Allen moved to CBS Radio’s KNX in Los Angeles, his music-and-talk half-hour format gradually changed to include more talk in an hour-long late-night format, boosting his popularity and creating standing-room-only studio audiences.

Allen’s first television experience came in 1949 when he answered an advertisement for a television announcer for professional wrestling. Although he knew nothing about wrestling, he watched some shows to gain insight, and discovered that the announcers did not have well-defined names for the wrestling holds. So, when he got the job he created names for many of the holds, some of which still are in use. After the first match got under way, Allen began ad-libbing in a comedic style that had audiences outside the arena laughing. An example:

Allen was an occasional actor. He wrote and starred in his first film, the Mack Sennett comedy compilation Down Memory Lane, in 1949. His most famous film appearance was in 1956’s The Benny Goodman Story, in the title role. The film, while an average biopic of its day, was heralded for its music, featuring many alumni of the Goodman band. Allen later recalled his one contribution to the film’s music, used in the early scenes. The accomplished Benny Goodman no longer could produce the sound of a clarinet beginner, and that was the only sound Allen was able to produce on a clarinet. In 1960, he appeared as the character “Dr. Ellison” in the episode “Play Acting” on CBS’s anthology series The DuPont Show with June Allyson though his The Steve Allen Show had been in competition with the program the preceding season.

After CBS radio gave Allen a weekly prime time show, CBS television believed he could be groomed for national television stardom and gave him his first network show. The Steve Allen Show premiered at 11 a.m. on Christmas Day, 1950, and was later moved into a thirty-minute, early evening slot. This new show required him to uproot his family and move from Los Angeles to New York due to technological limitations. The show ran until its cancellation in 1952, after which CBS tried several shows to showcase Allen’s talent.

According to his own estimate, Allen was a prolific composer who wrote more than 8,500 songs, although only a small fraction of them were ever recorded. In one famous stunt, he made a bet with singer-songwriter Frankie Laine that he could write 50 songs a day for a week. Composing on public display in the window of Wallach’s Music City, a Hollywood music store, Allen met the quota and won $1,000 from Laine. One of the songs, “Let’s Go to Church (Next Sunday Morning)” became a chart hit for the duo of Jimmy Wakely and Margaret Whiting, hitting #13 pop and #2 country in 1950.

Allen began his recording career in 1951 with the album Steve Allen At The Piano for Columbia Records. He then signed with Decca Records, recording for their subsidiaries Brunswick Records and then Coral Records. Allen would release a mixture of novelty singles, jazz recordings and straight pop numbers for Decca throughout the 1950s, before switching to Dot Records in the 1960s.

Leaving CBS, Allen created a late-night New York talk/variety television program that debuted in June 1953 on local station WNBT-TV (now WNBC-TV). The following year, on September 27, 1954, the show went on the full NBC network as The Tonight Show, with fellow radio personality Gene Rayburn (who later went on to host hit game shows such as Match Game, 1962–1982) as the original announcer. The show ran from 11:15 p.m. to 1 a.m. on the East Coast.

Allen’s second wife was actress Jayne Meadows, sister of actress Audrey Meadows. That union produced one son, Bill Allen, named for Steve’s father. They were married in Waterford, Connecticut, on July 31, 1954, and remained married until his death in 2000. He was a Democrat; his wife was a Republican. In the later 1950s, author and philosopher Gerald Heard worked with psychiatrist Sidney Cohen to introduce intelligent, adventurous people to LSD, and Steve Allen was one of these.

In June 1956, NBC offered Allen a new prime-time, Sunday night variety hour, The Steve Allen Show. NBC’s goal was to dethrone CBS’s top-rated The Ed Sullivan Show. The show included a typical run of star performers, including early television appearances by rock and roll pioneers Elvis Presley, Jerry Lee Lewis, and Fats Domino. Many popular television and film personalities were guest stars, including Bob Hope, Kim Novak, Errol Flynn, Abbott and Costello, Esther Williams, Jerry Lewis, Martha Raye, the Three Stooges, and a host of others.

Allen wrote the lyrics for the standard “Theme from Picnic”, which was a No. 13 U.S. hit in a vocal version for The McGuire Sisters in 1956. The song, however, is chiefly remembered as an instrumental, often performed in a medley with “Moonglow,” both songs created for the film Picnic in 1955. Two instrumental versions charted in the U.S. top 5 in 1956, including a No. 1 hit version by Morris Stoloff. Because he did not write the music, Allen was not credited as a songwriter on the instrumental versions.

In 1957, Jerry Vale had a minor hit (US #52) with the Allen composition “Pretend You Don’t See Her”. The song was later covered by Bobby Vee, who would also chart with it (US #97) in 1965.

Allen remained host of “Tonight” for three nights a week (Monday and Tuesday nights were taken up by guests hosts for most of the summer of 1956; then by Ernie Kovacs through January) until early 1957 when he left the show to devote his attention to the Sunday night program. It was his (and NBC’s) hope that The Steve Allen Show could defeat Ed Sullivan in the ratings. Nevertheless, Maverick often bested both in audience size. In September 1959, Allen relocated to Los Angeles and left Sunday night television (the 1959–’60 season originated from NBC Color City in Burbank as The Steve Allen Plymouth Show, on Monday nights). Back in Los Angeles, he continued to write songs, hosted other variety shows, and wrote books and articles about comedy.

Allen first had the concept for the show in 1959, but took almost 20 years to make it become reality. He initially produced a version in 1971 that aired locally in Los Angeles and earned three Local Emmy Awards. But, although it received critical acclaim from Hollywood critics, the distributor chose not to broadcast it nationally, feeling it would not draw a large enough audience. Even PBS backed off on showing it, and many in the television industry felt the series was “too thoughtful” for the American public. Allen then produced the first shows at his own expense, which resulted in attracting major backers. It eventually aired nationally, beginning in 1977.

After being cancelled by NBC in 1960, the show returned in the fall of 1961—on ABC. Nye, Poston, Harrington, Dell, and Dayton Allen returned. New cast members were Joey Forman, Buck Henry, the Smothers Brothers, Tim Conway, and Allen’s wife Jayne Meadows. The new version was cancelled after fourteen episodes.

Allen hosted a number of television programs up until the 1980s, including The New Steve Allen Show in 1961 and the game show I’ve Got a Secret (replacing original host Garry Moore) in 1964. In the summer of 1967, he brought most of the regulars from over the years back with The Steve Allen Comedy Hour, featuring the television debuts of Rob Reiner, Richard Dreyfuss, and John Byner, and featuring Ruth Buzzi, who would become famous soon after on the comedy ensemble show Rowan & Martin’s Laugh-In. In 1968 through 1971, Allen returned to syndicated nightly variety/talk with the same wacky stunts that would influence David Letterman in later years, including becoming a human hood ornament, jumping into vats of oatmeal and cottage cheese, and being slathered with dog food before allowing dogs backstage to feast on the food. During the run of this series, Allen also introduced Albert Brooks and Steve Martin to national audiences for the first time.

“Gravy Waltz” was composed and originally performed by Ray Brown as an instrumental in the early 1960s. Allen later set words to it, and the collaboration won the 1964 Grammy Award for Best Original Jazz Composition. Issued as an instrumental single in 1963, it hit #64 on the US Billboard charts. Though the single version was credited to “Steve Allen With Donn Trenner And His Orchestra,” Allen did not play on it. As well, though Allen was credited as co-songwriter for his lyrics, the hit single version was strictly an instrumental performance.

In the realm of theatre, Allen wrote the music and lyrics for the Broadway musical Sophie, which was based on the early career of the woman long billed as “The Last of the Red-Hot Mamas,” entertainer Sophie Tucker. The book for the show was by Philip Pruneau. Libi Staiger and Art Lund were featured in the leading roles. “Sophie” opened at the Winter Garden Theatre in New York, after tryouts in three other cities, on April 15, 1963, to mostly unfavorable critical notices. It closed five days later, on April 20, after just eight performances. As Ken Mandelbaum noted in his 1991 book “Not Since Carrie” –

Allen also was a regular on the popular panel game show What’s My Line? from 1953 to 1954, and returned frequently as a panelist until the series ended in 1967. Steve was sometimes jokingly referred to as the son of fellow panelist Fred Allen, but the two men were unrelated. He is also credited with reviving and popularizing the phrase “Is it bigger than a breadbox” while questioning contestants on What’s My Line?.

A similar Canadian television series called Witness to Yesterday, created by Arthur Voronka, aired three years after Allen’s Local Emmy Award-winning program. Allen appeared on a 1976 episode of Witness to Yesterday as composer-pianist George Gershwin.

A syndicated version of I’ve Got A Secret hosted by Allen and featuring panelists Pat Carroll and Richard Dawson was taped in Hollywood and aired during the 1972–1973 season. In 1977, he produced Steve Allen’s Laugh-Back, a syndicated series combining vintage Allen film clips with new talk-show material reuniting his 1950s television gang. From 1986 through 1988, Allen hosted a daily three-hour radio comedy show heard nationally on NBC that featured sketches and America’s better-known comedians as regular guests. His co-host was radio personality Mark Simone, and they were joined frequently by comedy writers Larry Gelbart, later of M*A*S*H writing fame; Herb Sargent, perhaps later on best known for his writing work on “Saturday Night Live,” and Bob Einstein, brother of Albert Brooks and creator and portrayer of the faux stuntman character Super Dave Osborne.

From 1977 until 1981, Allen wrote, produced and hosted the award-winning show Meeting of Minds, which aired on the Public Broadcasting Service (PBS). The series pitted the likes of Socrates, Marie Antoinette, Thomas Paine, Sir Thomas More, Attila the Hun, Karl Marx, Emily Dickinson, Charles Darwin, and Galileo Galilei, all of whom were acting as if brought back from the past. Their dialogue and heated arguments covered issues such as racism, women’s rights, crime and punishment, slavery, and religious toleration.

The series, consisting of six hour-long specials, became enormously popular. As a result, Allen received a Personal Peabody Award in 1977 for creating and hosting “a truly original show.” The award also recognized Meadows for her various portrayals. In 1981, the show won an Emmy for Outstanding Informational Series, and Allen’s writing was Emmy nominated. It was the show Allen wanted to be remembered for, because he believed the issues and characters were timeless and would survive long after his death.

By the 1970s, Allen was no longer actively recording his music. He continued to compose material, however, and in 1985, Allen wrote 19 songs for Irwin Allen’s television mini-series Alice in Wonderland. The series starred his wife Jayne Meadows as the Queen of Hearts, among countless other celebrities.

In 1986, Allen was inducted into the Television Hall of Fame.

After a long layoff from recording, in 1992 Allen issued the instrumental album Steve Allen Plays Jazz Tonight, which included interpretations of jazz classics as well as a handful of new original compositions.

Allen (who last guest hosted The Tonight Show in 1982) made a last appearance on The Tonight Show on September 27, 1994, for the show’s 40th anniversary broadcast. Jay Leno was effusive in praise and actually knelt and kissed Allen’s ring.

One notable program, which Westinghouse refused to distribute, featured Lenny Bruce during the time the comic repeatedly was being arrested on obscenity charges. Footage from this program was first telecast in 1998 in a Bruce documentary aired on HBO. Regis Philbin briefly took over hosting the Westinghouse show in 1964.

During the late 1980s, Allen and Jayne Meadows, his second wife, made three appearances on the television drama series St. Elsewhere. They played the estranged birth parents of the character Dr. Victor Ehrlich, who had given him up for adoption. And, in 1998, Allen and Meadows guest starred in an episode of Homicide: Life on the Street.

Working with Paul Kurtz, publisher of Prometheus Books, Allen published 15 books, including Dumbth: The Lost Art of Thinking with 101 Ways to Reason Better and Improve Your Mind, which was reissued in 1998. He produced Gullible’s Travels, an audiotape with original music and script that was read and sung by him and his wife “in order to introduce youngsters to the brain and its proper use.” Wishing to counter the influence of the American Christian right, Allen wrote both a 1990 critique of the Bible (Steve Allen on the Bible, Religion and Morality) as well as a sequel. A sample passage from the book that illustrated his view of the Judeo-Christian God reads:

Although Allen had received a Roman Catholic upbringing, he later became a secular humanist and Humanist Laureate for the Academy of Humanism, a member of CSICOP and the Council for Secular Humanism. He received the Rose Elizabeth Bird Commitment to Justice Award from Death Penalty Focus in 1998. He was a student and supporter of general semantics, recommending it in Dumbth and giving the Alfred Korzybski Memorial Lecture in 1992. In spite of his liberal position on free speech, his later concerns about the lewdness he saw on radio and television, particularly the programs of Howard Stern, caused him to make proposals restricting the content of programs, allying himself with the Parents Television Council. His full-page ad on the subject appeared in newspapers just before his unexpected death.

Allen died on October 30, 2000, at the age of 78. At first, it was suspected he had suffered a fatal heart attack while napping at his son’s Los Angeles area home. However, a Los Angeles Coroner’s spokesperson later said autopsy results showed the real cause of death was a ruptured blood vessel caused by chest injuries he did not realize he had sustained in a minor traffic accident earlier in the day. According to Jayne Meadows, “Typical of Steve, [who] was the dearest, sweetest man: He was hit by a man, backing into him, breaking all of his ribs, that pierced his heart … and when he got out of the car, he said to the man, ‘What some people will do to get my autograph’.”

In 2011 Allen was selected for inclusion in the Committee for Skeptical Inquiry’s Pantheon of Skeptics.

He is buried at Forest Lawn Memorial Park (Hollywood Hills) in Hollywood Hills, Los Angeles. He has two stars on the Hollywood Walk of Fame – a television star at 1720 Vine Street and a radio star at 1537 Vine Street. Jayne Meadows was buried next to Allen following her death in 2015.

On June 25, 2019, The New York Times Magazine listed Steve Allen with hundreds of artists whose material was reportedly destroyed in the 2008 Universal fire.