Great niece Robin Randall says Schwartz died of natural causes at 4 a.m. Tuesday at Cedars Sinai Medical Center. He's survived by his wife of 69 years and four children.
Schwartz changed the landscape of American television. The producer, writer and composer received his star on the Hollywood Walk of Fame in 2008.
He began his career in 1939, writing for Bob Hope's radio show. Schwartz went on to write for TV shows, including "The Adventures of Ozzie and Harriet," before creating his own.
"Gilligan's Island" ran from 1964 to 1967, and was revived in later years with three made-for-TV movies. He followed that series up with the hugely successful family comedy, "The Brady Bunch."
Success was the hallmark of Schwartz's own career. Neither "Gilligan" nor "Brady" pleased the critics, but both managed to reverberate in viewers' heads through the years as few such series did, lingering in the language and inspiring parodies, spinoffs and countless standup comedy jokes.
One of the surviving stars, Tina Louise, tweeted, "Sherwood Schwartz brought laughter and comfort to millions of people. Gilligan's Island was a family. He will be in our hearts forever."
"Brady Bunch" star Florence Henderson said Schwartz changed her life by casting her, calling him a "wonderful teacher" who will be missed by so many.
That includes Barry Williams, who played Henderson's son, Greg Brady, in the series.
"He was a very considerate man, someone who always listened to us kids. If we had ideas and things, he took us seriously and respectfully," he said. "I think the most important thing I would like fans to know about Sherwood is he was the real deal. He was authentic."
His nephew, Douglas Schwartz, who created the hit series "Baywatch," called his uncle a longtime mentor and caring "second father" who helped guide him successfully through show business.
Sherwood Schwartz was born in 1916 in Passaic, N.J., and grew up in Brooklyn, N.Y.
The Associated Press contributed to this report.