He was born Edward Byrne Breitenberger. He had two siblings, Vincent and Jo-Ann. When he was 13, his father died. He then dropped his last name in favor of "Byrnes" based on the name of his maternal grandfather, Edward Byrne, a fireman.
Byrnes's most famous role was as Gerald Lloyd "Kookie" Kookson III, on the ABC/Warner Brothers detective series 77 Sunset Strip. In the pilot for the series, Girl on the Run, Byrnes played a continually hair-combing contract killer. The character became an immediate national teen sensation, prompting the producers to make Byrnes a regular cast member. They transformed Kookie from a hitman into a parking valet at a nearby restaurant who helped as a private investigator. Efrem Zimbalist, Jr., explained the situation to the audience:
We previewed this show, and because Edd Byrnes was such a hit, we decided that Kookie and his comb had to be in our series. So this week, we'll just forget that in the pilot he went off to prison to be executed.
Kookie's recurring character—a different, exciting look that teens of the day related to—was the valet-parking attendant who constantly combed his piled-high, greasy-styled teen hair, often in a windbreaker jacket, who worked part-time at the so-called Dean Martin's Dino's Lodge restaurant, next door to a private-investigator agency at 77 Sunset Strip in West Hollywood. Kookie frequently acted as an unlicensed, protégé detective who helped the private eyes (Zimbalist and Roger Smith) on their cases, based upon "the word" heard from Kookie's street informants. Kookie called everybody "Dad" (as in "Sure thing . . . Dad") and was television's homage to the "Jack Kerouac" style of cult-hipster of the late 1950s.
To the thrill of teen viewers, Kookie spoke a jive-talk "code" to everyone, whether you understood him or not, and Kookie knew, better than others, "the word on the street." Although the Kookie character was at least several years older than Jim Stark, James Dean's character in the film "Rebel Without a Cause," Byrnes exuded a similar sense of cool. Kookie was also the progenitor of Henry Winkler's The Fonz character of the Happy Days series (switch hot rod for motorcycle; same hair and comb).
Kookie's constant onscreen tending of his ducktail haircut led to many jokes among comedians of the time, and it resulted in the 1959-charted (13 weeks) 'rap' style recording, "Kookie, Kookie—Lend Me Your Comb," recorded with actress and recording artist Connie Stevens, and which reached #4 on the Billboard Hot 100. It sold over one million copies and was awarded a gold disc by the RIAA. The song also appeared on the Edd Byrnes album, entitled (what else) Kookie. He and Stevens appeared together on ABC's The Pat Boone Chevy Showroom. During the run of 77 Sunset Strip, Byrnes, as the "Kookie" character, was a popular celebrity (Elvis Presley–level national attention), and Byrnes received fan-mail volume that reached 15,000 letters a week, according to Picture Magazine in 1961, rivaling most early rock-recording stars of the day.
Byrnes walked off the show in the second season, demanding a bigger part and higher pay; the producers eventually agreed. He appeared as a guest star in other WB series, including Lawman and Sugarfoot, in the latter with John Russell, Rodolfo Hoyos, Jr., and Will Wright in the 1958 season-premiere episode "Ring of Sand."
Owing to restrictions in his Warner Brothers television contract, Byrnes was forced to turn down film roles in Ocean's Eleven (1960), Rio Bravo (1959), North to Alaska (1960), and The Longest Day (1962). However, he appeared in the Warner Brothers films Darby's Rangers (1957; replacing Tab Hunter), Marjorie Morningstar (1958), and Up Periscope and Yellowstone Kelly (both 1959). He tested for the role of John F. Kennedy in PT 109, but President Kennedy preferred Cliff Robertson.
Although Byrnes was a popular celebrity, the years of unfortunate "Kookie" typecasting led him to ultimately buy out his television contract with Warner Brothers to clear his way for films—though it was accomplished too late to allow Byrnes to capitalize on feature-length-cinema projects based upon his established television-series fame.
Byrnes travelled to Europe where he made several films. He was featured as one of the convict commandos in 1964 in Roger Corman's The Secret Invasion. In 1965 he played Dick Martin in Beach Ball, then returned to Europe for several spaghetti westerns, including the 1967 films Renegade Riders, Any Gun Can Play and Red Blood, Yellow Gold.
Since then, Byrnes appeared in many television programs and movies, including the "Duo-Vision" horror film Wicked, Wicked in 1973, and as a TV interviewer in the David Essex film Stardust (1974). He played the role of the Dick Clark-like dance-show host Vince Fontaine, host of National Bandstand, in the 1978 movie Grease. Byrnes also appeared in Mankillers (1987), Back to the Beach (1987) and Troop Beverly Hills (1989).
In 1974, Byrnes hosted the pilots of Wheel of Fortune.
As a tribute to his enduring celebrity and his iconic "Kookie" character, Byrnes has ranked #5 in TV Guide's list of "TV's 25 Greatest Teen Idols" (23 January 2005 issue). He wrote an autobiography in 1996 entitled Kookie No More.
Byrnes' son by Asa Maynor is Logan Byrnes, a television news anchor for Fox-11 News in Los Angeles, California. Previous to 2016, he was at Fox Connecticut since 2008.
Byrnes appeared during the Memphis Film Festival in June 2014, in which he was reunited with his former Yellowstone Kelly co-star Clint Walker. Prior to the launching of 77 Sunset Strip, he appeared in several episodes of Cheyenne.