Carlin, who had a history of heart problems, died at St. John's Health Center in Santa Monica shortly before 6 p.m., said his publicist Jeff Abraham.
He finished a show at the Orleans casino in Las Vegas last week and was planning to take the month off to relax and work on a new book of essays and musings, Abraham said.
Carlin normally took summers off and was scheduled to tour again beginning with a July 20 performance at Humphrey's Concerts by the Bay in San Diego. He had dates lined up through December, Abraham said.
"He was looking forward to it."
Carlin went to the hospital Sunday afternoon because "his heart just didn't feel right," the publicist said.
Carlin starred in a variety of TV and movie roles and gained fame for a routine about the seven dirty words that could not be uttered on television.
"There are three ingredients in my comedy," he said in a 1991 interview with the Los Angeles Times. "Those three things which wax and wane in importance are English language and wordplay; secondly, mundane, everyday observational comedy -- dogs, cats and all that stuff; and thirdly, sociopolitical attitude comedy."
He earned several gold comedy albums and five Emmy nominations.
Carlin was arrested in 1972 in Milwaukee for using indecent language. In a separate case in 1973, a radio listener complained after a station played part of his album. That case went the Supreme Court, which in 1978 ruled in favor of the FCC, saying the radio station could not broadcast those words at times when children could be listening.
Of the Surpeme Court ruling, Carlin said, "So my name is a footnote in American history, which I'm perversely kind of proud of."
Carlin first appeared on radio in 1956 at age 19, while serving in the Air Force.
In 1960, he and Jack Burns began appearing together in nightclubs as "Burns and Carlin." The duo made an appearance on The Tonight Show with Jack Paar before splitting up in 1962.
Carlin became a hit on the college circuit. He survived cocaine dependency in the 1970s and a heart attack and two open-heart surgeries in the 1980s.
In the 1990s he added acting to his schedule, appearing in the Barbra Streisand-Nick Nolte movie "Prince of Tides." Other film roles came in "Bill and Ted's Excellent Adventure" and "Dogma," with Matt Damon and Ben Affleck.
He was the first host of "Saturday Night Live" and appeared some 130 times on "The Tonight Show."
He authored three books, including "Brain Droppings," a collection of essays and routines, and "Napalm and Silly Putty," a collection of his stand-up material. Both won Grammy awards. His third book, "When Will Jesus Bring the Pork Chops?" was nominated for a Grammy.
The death of his wife of more than 30 years, Brenda Hosbrook Carlin, on Mother's Day 1997 was particularly hard for Carlin. "See ya Dink," he wrote on his website. "Miss you a lot."