Andy Williams, whose languid crooning style and disarming presence propelled him to recording and television stardom in the 1960s, with hits including “Moon River” and the inescapable holiday jingle “It’s the Most Wonderful Time of the Year,” died Sept. 25 at his home in Branson, Mo. He was 84.

He died after a year-long battle with bladder cancer, his publicist, Paul Shefrin, said.

Mr. Williams’s entertainment career spanned eight decades, starting when he was an 8-year-old singer performing at church socials in his native Iowa. With his radiant smile, chiseled dimples and earnest personality, he conveyed an unfailingly wholesome image throughout his career — sometimes to his dismay. All too often, he wrote in his memoir, he was perceived as a “farm boy in a tuxedo.”

There was a seemingly effortless warmth in Mr. Williams’s tenor voice, but it was a hard-earned achievement after years of practice in small clubs and on the road. “You have to practice harder, because you’re not as good as the others out there,” his father had told him as a child. It stoked a lifelong desire to excel but also to please.

“I still think I’m not as good as anybody else,” he told an interviewer as he approached retirement after a career in which he sold many millions of records.

Mr. Williams’s heyday spanned the life of his musical variety TV program, “The Andy Williams Show,” which aired on NBC from 1962 to 1967 and again from 1969 to 1971. The Christmas specials that spun off from the show ran for decades afterward, featuring celebrity carolers as well as members of the Williams family. The specials became television staples for generations of viewers and epitomized the season as much as department store Santas.

In a varied show business career, Mr. Williams headlined at major venues such as the Copacabana in New York and Caesars Palace casino in Las Vegas, sang at three Academy Awards ceremonies in the 1960s, hosted the first live telecast of the Grammy Awards in 1971, and headlined the halftime show of Super Bowl VII in 1973. After the assassination of his friend Robert F. Kennedy in 1968, Mr. Williams sang “The Battle Hymn of the Republic” at the funeral.

There were early attempts to make Mr. Williams a rock star in the Elvis Presley mold; one rock-tinged song, “Butterfly,” rose to No. 1 on the pop charts in 1957. He also ventured promisingly into jazz with his 1961 album “Under Paris Skies,” with Quincy Jones conducting the orchestra.

But Mr. Williams found his greatest commercial success in the 1960s and early 1970s with anodyne pop and yuletide music, which yielded more than a dozen hits. During this period, he recorded or popularized a slew of lush, orchestra-backed movie themes. Besides his signature number “Moon River” (from “Breakfast at Tiffany’s”), Mr. Williams recorded “Days of Wine and Roses,” “Born Free,” “The Shadow of Your Smile” (from “The Sandpiper”), “Charade,” the theme from “Love Story,” and a love ballad from “The Godfather” known as “Speak Softly Love.”

As a television show host, Mr. Williams followed in the easygoing tradition of “The Perry Como Show.” The program, whose producers included future “All in the Family” creator Norman Lear, was a highly visible platform for newer talent. Guests included the Osmond Brothers, the Jackson 5 and Simon and Garfunkel. Mr. Williams’s potpourri of entertainers also featured singer-actress Julie Andrews and comedians Woody Allen and Phyllis Diller.

As a nod to the zanier doings on the popular sketch show “Rowan & Martin’s Laugh-In,” Mr. Williams began to feature oddball recurring characters.

“There was the Cookie Bear, a poor guy in a bear suit who couldn’t get any sound from a mike inside the muzzle, so the voice was done by the producer,” he told the London Independent in 2001. “We also had a midget in a German helmet who’d hit me in the knee with a wooden hammer. And the Walking Suitcase, with a guy bent up inside it.”

Robert Thompson, a pop culture historian at Syracuse University, said the show “represented the pleasant last gasp of what we used to think of as mass culture” before the rise of more socially topical and subversive humor on “All in the Family” and “M*A*S*H.”

Mr. Williams remained a major recording star for several years and continued to sing concerts well into the 2000s at the Moon River Theatre, a complex he built in the Ozarks town of Branson.

He received an unexpected burst of attention when his groovy, finger-snapping recordings of “Music to Watch Girls By” and “Can’t Take My Eyes Off You” from 1967 were revived in the late 1990s for TV advertising campaigns for Fiat and Peugeot, respectively.

The ads briefly transformed Mr. Williams into the hippest grandfather of the moment. He was booked on concert tours of Europe and Asia, where women threw panties at him onstage for the first time in his career.

“I had never had that kind of reaction before, though that might have been partly due to the material I sang,” he wrote in his 2009 memoir, “Moon River and Me.” “Andy Williams crooning ‘Danny Boy’ didn’t have quite the raunch factor of Tom Jones belting out ‘Sex Bomb.’

Howard Andrew Williams was born Dec. 3, 1927, in Wall Lake, Iowa. His father, Jay Williams, was a railway mail clerk who trained the Williams children to sing in the choir of the local Presbyterian church. Their skill at harmonizing led their father to think they were destined for greatness.

By the late 1930s, the Williams Brothers — Andy and his older siblings Richard, Robert and Donald — began singing on the radio in Des Moines. The family eventually settled in Los Angeles, so the boys could break into film. The Williams Brothers accompanied Bing Crosby on the 1944 pop hit “Swinging on a Star,” an Oscar-winning song Crosby also sang in the film “Going My Way.”

Although he did not appear in that movie, Mr. Williams was the subject of enduring curiosity for one of his earliest forays into screen work. At 16, he was asked to dub Lauren Bacall’s voice in the song “How Little We Know” for her film debut in “To Have and Have Not” (1944). Bacall and director Howard Hawks denied that the final cut included Mr. Williams’s voice. Mr. Williams remained coy.

“I really wish, now, it had never happened, because now when people ask me if that’s my voice on the screen I have to compromise and say ‘maybe,’ ” he told the Tulsa World in 2000.

From 1947 to 1953, the Williams Brothers teamed on and off with the comedienne and future “Eloise” author Kay Thompson in her widely lauded nightclub act, which transformed music, pantomime and pratfalls into high art and packed large theaters from Hollywood to Paris.

After the brothers went their own ways professionally, Andy Williams’s regular appearances on Steve Allen’s “Tonight” show in the mid-1950s launched his solo recording career. He flourished as a pop star with million-selling singles including “Canadian Sunset” and “The Hawaiian Wedding Song.” “I Like Your Kind of Love,” “Butterfly,”

Mr. Williams was discreet about his personal life. In his memoir, he disclosed a long affair in the 1950s with Kay Thompson, who was nearly 20 years his senior.

In 1961, he married the whispery-voiced Claudine Longet, a French-born Las Vegas showgirl who became a singer and actress. The marriage produced three children — Noelle, Christian and Robert — before ending in divorce.

Longet later became a subject of notoriety for fatally shooting her lover, the ski champion Vladimir “Spider” Sabich, at their Aspen, Colo., home in 1976. She claimed that the gun fired accidentally. Mr. Williams testified on his ex-wife’s behalf and, in 1977, a judge sentenced her to 30 days in jail for criminally negligent homicide, a misdemeanor.

In 1991, Mr. Williams married Debbie Haas and lived with her in Branson. Besides his wife, survivors include his three children from his first marriage.

Mr. Williams could be an easy target for satirists. The brightly colored cardigans and turtlenecks that he trotted out for Christmas shows have, in recent years, been lampooned by Comedy Central’s faux-conservative talk-show host Stephen Colbert.

But if Mr. Williams was perceived as unhip, he was deliberately so. He decided long ago that to sustain a long career, it was wise to avoid the vagaries of the avant garde and ever-shifting youth fads.

“I wouldn’t want to sing solely for teenagers,” he said in 1958. “Once they go to college, their musical taste changes, and then where would I be?”