Berenstain, a longtime resident of Solebury in southeastern Pennsylvania, suffered a severe stroke on Thursday and died Friday without regaining consciousness, her son Mike Berenstain said.
The gentle tales of Mama Bear, Papa Bear, Brother Bear and Sister Bear were inspired by the Berenstain children, and later their grandchildren. The stories address children's common concerns and aim to offer guidance on subjects like dentist visits, peer pressure, a new sibling or summer camp.
The first Berenstain Bears book, "The Big Honey Hunt," was published in 1962. Over the years, more than 300 titles have been released in 23 languages -- most recently in Arabic and Icelandic -- and have become a rite of passage for generations of young readers.
"They say jokes don't travel well, but family humor does," said Jan Berenstain told The Associated Press in 2011. "Family values is what we're all about."
Stan and Jan Berenstain, both Philadelphia natives, were 18 when they met on their first day at art school in 1941.
They married in 1946, after Stan Berenstain returned home from serving as a medical illustrator at a stateside Army hospital during World War II. During that time, Jan Berenstain worked as a draftsman for the Army Corps of Engineers and as a riveter building Navy seaplanes.
Before their family of bear books was born, the young couple had already built a successful career in periodicals. A cartoon series they produced called "All in the Family" ran in McCall's and Good Housekeeping magazines for 35 years, and their art appeared in magazines including Collier's and The Saturday Evening Post.
Stan and Jan Berenstain created hundreds of books until Stan Berenstain's death in 2005 at the age of 82.
Mike Berenstain is an illustrator who collaborated on the books with his mother in recent years. His elder brother, writer Leo Berenstain, is involved with the business end of the family franchise.
The books in recent years have tackled modern subjects such as online safety and childhood obesity, and the bears (or their human helpers) answer children's emails and letters, but the goal is to tell enduring, universal stories. Perennial favorites cover challenges of getting kids to doing chores, defuse fears of the first day of school and teach values of kindness and generosity.
"It's wonderful to do something you love for so many years," Jan Berenstain told the AP in 2011. "Not everyone has that."
About 260 million copies of Berenstain Bears books have been held in the hands of children and their parents since the earliest books were published with the help of Theodor Geisel, a children's books editor at Random House better known as Dr. Seuss.
Mike Berenstain said his mother worked daily at her home studio in an idyllic part of Bucks County, north of Philadelphia, which served as inspiration for the books' setting. He said he will continue writing and illustrating future Berenstain books.
"Every day she was very productive," he said. "She was working on two books and had been doing illustrations until the day before she passed away."
Jan Berenstain is survived by her two sons and four grandchildren.