The Little Women leading lady, 25, debuted baby bangs when she stepped out onto the red carpet in a peplum Gucci gown at the 92nd annual Academy Awards on Sunday.
Ronan's hairstylist Adir Abergel, who styles the tresses of the biggest A-list stars from Reese Witherspoon to Anne Hathaway, revealed to ET they are indeed "real bangs" and were cut "on the morning of" the awards show.
"When I saw [Saoirse's] dress I immediately thought of a modern day Audrey Hepburn, and I thought how do we actually kind of go there and make them, but make them a little bit cooler, a little bit more notched in," Abergel explained during ET Style Feed's Oscars recap on Monday morning. "And we saw a lot of that actually on the runway last year and so I think that it's become like this big trend."
"I approached her and she was totally into it," he added.
Abergel, who has been working with Ronan since she was 8 years old, admitted he was nervous about the quick cut, but he was very happy with the result.
"I think she just looks gorgeous and it's beautiful and she's in Gucci and it just feels cool and it feels young and it feels fun and it feels like it's like, I don't know -- it just feels modern for the Oscars."
After giving Ronan some fringe that morning, Abergel raced to his next client -- another Best Actress nominee, Charlize Theron.
The Bombshell star has long been the subject of the hairstylist's creations -- he's the one responsible for her viral bowl haircut.
"Charlize is one of these incredibly bold, transformative women who really allows me to have my creativity. She's willing to take a risk," Abergel shared.
Theron only had an hour and a half to spare before heading to the red carpet. After fighting through the rain and LA traffic, Abergel went to work on her short bright blonde crop.
The final look was a sleek 'do that complimented her elegant Dior asymmetric gown. Look closely at the back and you can see the chic detail.
"I basically took extensions and put them on either side of where the parting was and then I got the hair very, very long and then I took black thread and I bound the extension and then I just kind of tied them together and had it fall into a half moon almost, in the back," Abergel said.
Abergel went on to explain the trust his clients have in his expertise and imagination for hair.
"You know what's really incredible is there is a beautiful trust that happens with your clients and most of my girls -- you know Jen Garner I've been working with 20 years and Jessica Biel and Reese Witherspoon -- they're clients of 20 years, so there is a beautiful exchange that happens where there is a trust."
Watch ET Style Feed's full Oscars beauty recap with Abergel, celebrity stylist Marni Senofonte, model Tess Holliday and Love Island host Arielle Vandenberg in the video above.