Adams died Wednesday in a Los Angeles hospital from pneumonia and cancer, publicist Henri Bollinger said.
A graduate of Juilliard School of Music, Adams hoped to become an opera singer but instead went on to gain fame for her sketches with Kovacs and her pivotal roles in two top Broadway musicals.
For nearly two decades, she also was the sexy spokeswoman for Muriel cigars, singing and breathily cooing in TV commercials: "Why don't you pick one up and smoke it sometime?"
She was born Elizabeth Edith Enke in 1927 in Kingston, Pa., and grew up in Tenafly, N.J. She first attracted notice on the TV show "Arthur Godfrey's Talent Scouts." Kovacs was then performing his innovative comedy show on a Philadelphia TV station, and his director saw her and invited her to audition.
"Here was this guy with the big mustache, the big cigar and the silly hat," she recalled in 1982. "I thought, `I don't know what this is, but it's for me."'
When she auditioned for the Kovacs show, she knew a lot about opera but only three pop songs, she recalled.
"I sang them all during the audition, and if they had asked to hear another, I never would have made it," she said.
With her innocent face and refreshing manner, Adams became the ideal partner for Kovacs' far-out humor. They eloped to Mexico City in 1954.
Kovacs moved his show - which appeared in various guises in the 1950s and early 1960s - to New York, where he became the darling of critics and discriminating viewers and hugely influential on other comedians. Both Kovacs and Adams garnered Emmy nominations in 1957 for best performances in a comedy series.
Adams found success on Broadway as well.
She was acclaimed for her role as the sister to Rosalind Russell's character in the 1953 "Wonderful Town," the Comden-Green-Bernstein musical based on "My Sister Eileen."
In 1957, Adams won a Tony for best featured (supporting) actress in a musical for her role as Daisy Mae in "Li'l Abner," based on Al Capp's satirical comic strip.
"Edith Adams makes a wonderful Daisy Mae with her busty blouse, brief skirt and bare legs - the hill-billy girl with a touch of Al Capp's Hollywood glamour," The New York Times wrote.
She and Kovacs moved to Hollywood in the late 1950s, and both became active in films.
In Billy Wilder's classic "The Apartment," the 1960 Oscar winner for best picture, Adams played the spurned secretary to philandering businessman Fred MacMurray.
Among her other movies were "Lover Come Back," "Call Me Bwana" (with Bob Hope), the all-star comedy "It's a Mad, Mad, Mad, Mad World" (as Sid Caesar's wife), "Under the Yum Yum Tree," "The Best Man" and "The Honey Pot."
In early 1962, Kovacs left a star-filled baby shower for Mrs. Milton Berle and crashed his car into a light pole, dying instantly. He had been a carefree gambler and profligate buyer of unneeded things. He once telephoned his wife and said he had bought the California Racquet Club, with its nightclub, shops and mortgages.
His widow was faced with debts of $520,000, trouble with the Internal Revenue Service and a nasty custody battle over Kovacs' daughters, Betty and Kippie, from his first marriage. She and Kovacs also had a daughter Mia, born in 1959.
Berle, Frank Sinatra, Jack Lemmon, Dean Martin and other stars organized a TV special to raise money for her and her daughters.
"No," she said, "I can take care of my own children."
For a solid year, she worked continuously. She did movies, TV musical revues and a Las Vegas act where Groucho Marx introduced her with the comment: "There are some things Edie won't do, but nothing she can't do."
She won custody of her stepdaughters, tearfully telling reporters after the verdict: "This is the way Ernie would have wanted it."
Over a career that spanned some six decades, Adams also appeared in various stage productions; had a short-lived TV show in 1963 that earned her two Emmy nominations; performed in nightclubs and released several albums.
In the 1980s and 1990s, she made appearances on such TV shows as "Murder, She Wrote" and "Designing Women." She also played Tommy Chong's mother, Mrs. Tempest Stoner, in the first Cheech and Chong movie, "Up in Smoke," in 1978.
Over the years, she strove to keep Kovacs' comedic legacy alive by buying rights to his TV shows and repackaging them for television and videocassettes.
After her widowhood, she had two brief marriages to photographer Martin Mills and trumpeter Pete Candoli.
She is survived by her son, Joshua Mills. Daughter Mia Kovacs was killed at 22 in a 1982 car accident.