His mother Anna (née Geller) worked in the garment trades while his father Philip Hacker was a furniture upholsterer and part-time inventor.

[1][3] Hackett suffered from Bell's palsy as a child, the lingering effects of which contributed to his distinctive slurred speech and facial expression.

[3] Following his graduation from high school in 1942, Hackett enlisted in the United States Army and served during World War II for three years in an anti-aircraft battery.

There was an anecdote that, because of this appearance, Hackett received an offer to join the Three Stooges from Jules White, the head of Columbia short subject department, in 1952.

The routine was such a hit that Hackett made a recording of it, and was hired to reprise it in the Universal-International musical Walking My Baby Back Home (1953), in which he was third-billed under Donald O'Connor and Janet Leigh.

Abbott and Costello were set to make a feature-length comedy Fireman, Save My Child, featuring Spike Jones and His City Slickers.

Universal-International salvaged the project by hiring Hugh O'Brian and Hackett to take over the Abbott and Costello roles with Jones and his band becoming the main attraction.

Hackett became known to a wider audience when he appeared on television in the 1950s and 60s as a frequent guest on variety talk shows hosted by Jack Paar and Arthur Godfrey, telling brash, often off-color jokes, and mugging at the camera.

According to the board game Trivial Pursuit, Hackett has the distinction of making the most guest appearances in the history of The Tonight Show Starring Johnny Carson.

[12] He appeared with his roommate Lenny Bruce on the Patrice Munsel Show (1957-1958), calling their comedy duo the "Not Ready for Prime Time Players,"[4] twenty years before the cast of Saturday Night Live used the same name.

Then, Longden's former partner, George Tanner (Denver Pyle), comes to town but avoids confrontation with Bibs and accepts the explanation that Wicks' death was accidental.

[13] Hackett starred as the title character on NBC's Stanley, a 1956–57 situation comedy which ran for 19 weeks on Monday evenings at 8:30 pm ET.

Throughout the 1970s, Hackett published a book of poetry entitled The Naked Mind of Buddy Hackett,[14] made frequent appearances on Johnny Carson's Tonight Show until Carson's retirement in 1992, delivered a dramatic performance as Lou Costello in the television movie Bud and Lou opposite Harvey Korman as Bud Abbott, and narrated the Rankin/Bass Christmas special Jack Frost (1979).

Hackett appeared regularly in TV ads for Tuscan Dairy popsicles and yogurt throughout this decade, with his most famous television campaign being for Lay's potato chips ("Nobody can eat just one!

Hackett also appeared on The Love Boat, Murder, She Wrote, L.A. Law, and guest-starred in the Space Rangers episode "To Be Or Not To Be" as has-been comedian Lenny Hacker, a parody of his stage persona.