Berenstain wrote and illustrated the classic Berenstain Bears picture books with her husband Stan, who died in 2005 at age 82.
Mike Berenstain, who worked with his mother after his father died, told EW.com she suffered a stroke last Thursday and died the following day.
The first Berenstain Bears book, "The Big Honey Hunt," was published in 1962. More than 300 Berenstain books have been published since in more than 23 languages. There are more than 260 million copies in print, EW.com noted.