But the 73-year-old actress isn't afraid to mix things up every now and then. In fact, her latest style choice has her celebrity pals applauding.
On Sunday, the star posted a monologue online about a pair of wide-leg jeans she says have drawn significant attention in recent days. Keaton said she's worn the '90s-inspired denim, which many have claimed may be JNCO, to both run errands and attend events. After fielding several inquiries about the pants, Keaton decided to take to Instagram to show them off.
"REGARDING THESE PANTS: THIS IS SERIOUSLY TRUE. I WORE THEM ON THE PLANE. I WORE THEM IN THE HOTEL DUPONT. I WORE THEM IN THE DELAWARE ART MUSEUM. I WORE THEM ON A LONG WALK THROUGH THE WILMINGTON STREETS. I’M WEARING THEM ON THE TRAIN TO NYC. I’VE NEVER RECEIVED MORE COMPLIMENTS ON ANYTHING I’VE EVER WORN IN MY ENTIRE LIFE," wrote Keaton, along with two photos of herself in the belted jeans.
The images show Keaton posing front and back with her hands on her hips, wearing a black hat, black turtleneck and chunky boots.
As of Tuesday morning, Keaton's post has received more than 105,000 likes and hundreds of comments from fans and celebrities alike.
"Uh… they’re great because YOU’RE wearing them," commented former "Friends" star Lisa Kudrow.
"WHO MAKES THEM???" asked Gwyneth Paltrow, while Jennifer Garner echoed her friend's question: "Thank you, Gwyneth, WHO MAKES THEM?!!!"
"You are my hero!" exclaimed "Girlfriends" actress Tracee Ellis Ross.
Actress Debra Messing was enthralled with the pants' pockets.
"DIANE — you are the bomb! Who makes them? The pockets?!?!" asked Messing, adding a heart emoji.
Film director Nancy Meyers called the star "the coolest."
"Xo from a long time fan," signed Meyers, adding, "What’s happening in Delaware?"
Meyers worked with co-stars Keaton and Jack Nicholson on the romantic comedy "Something's Gotta Give" in 2003. In the film, Nicholson's character Harry pokes fun at Keaton's character Erica for always wearing turtlenecks.
"What's with the turtlenecks? It's the middle of summer," Harry asks Erica in the movie.
"I like them. I've always liked them, and I'm just a turtleneck kind of gal," Erica later replied.
It appears she still does. Keaton has yet to give her star-studded friend group an answer — until then, fans will have to try their best to replicate the look without guidance.