The supermodel told the tale of how their romance came to be on Thursday's episode of The Tonight Show.
The two met on a blind date in 2006.
"For some reason, everybody thought they needed to find me a boyfriend," she said. "So, actually, it was my third blind date."
After a few failed dinner dates with her other suitors, Bündchen decided to grab a drink with Brady, thinking she could come up with an easier exit strategy if the date was a dud. However, she soon learned this wouldn't be necessary.
"When I saw those kind eyes, I literally [fell] in love, like, right away," she recalled.
Still, their relationship didn't get off to an easy start. The celebrity soon felt like her "world had been turned upside down" after she learned the quarterback's ex-girlfriend, Bridget Moynahan, was pregnant with his child.
"Needless to say, that wasn't an easy time," she wrote in her new book Lessons: My Path to a Meaningful Life. "But it was a time that brought about so much growth."
In August 2007, Moynahan gave birth to a baby boy named Jack, whom Bündchen would later refer to as her "bonus child." The model claimed the birth made her "heart expand in ways I didn't know was possible." She also wrote that Jack "has been a huge gift and blessing."
Bündchen and Brady married in 2009. They've since welcomed two more kids: Vivian and Benjamin.