The 54-year-old actress stops by The Ellen DeGeneres Showon Thursday and reveals that she had a major crush on Reeves when they teamed up for Speed in 1994.
The action flick is gearing up to celebrate its 25th-anniversary next summer and, when DeGeneres asks her what she remembers most from her breakout role, Bullock gives only one answer: Reeves.
"I think about how sweet Keanu Reeves was and how handsome he was," she gushes. "It was hard. It was really hard for me to really be serious. He'd look at me and I'd [giggle]."
Bullock even gave her crush an all-important job during the film's stunts.
"My dress sort of kept flying up and I said, 'Whatever you do, just keep my dress down,'" she recalls. "The whole stunt he just made sure my dress [stayed down]. It was very sweet."
Despite her infatuation, the pair never dated, something Bullock jokingly blames on herself. "There was just something about me that I guess he didn't like," she says with a laugh. "I think it's true."
"He was probably intimidated," DeGeneres reasons, prompting Bullock to disagree.
The co-stars went on to remain friends, even making a second movie -- The Lakehouse -- together in 2006. That happened, Bullock muses, because they never got out of the friend zone.
"I think we're probably friends for that long because we didn't..." Bullock says with a giggle and a not-so-subtle wink.
"Is that how you do it?" DeGeneres asks, mimicking Bullock's over-the-top facial expression.
"That's how I do it," she confirms.
"Maybe that's why he didn't want to be with you," the host quips.
ET caught up with the actress earlier this month at the premiere of her latest flick, Bird Box. While there, Bullock revealed why she does better work when her kids -- Louis, 8, and Laila, 6 -- are on set.
Watch the video below to hear what she had to say: