Jason, 32, proposed to the Season 11The Bachelorette star, 35, in Nashville, TN, on Monday afternoon while the pair was recording an episode of Kaitlyn's Off the Vine podcast, Entertainment Tonightreported.
"It was everything I could have asked for," Kaitlyn gushed to ET.
"The words that came out of his mouth were insanely beautiful. We've never locked eyes like that in our lives. We were holding hands, so intense, and I was listening to his every word, but still blacked out."
Kaitlyn recalled how Jason seemed really nervous at the start of their podcast episode but she had "zero" idea a marriage proposal was coming.
Kaitlyn was reportedly told they'd be interviewing a special surprise guest but then Jason popped the question about 30 minutes into filming.
"Jason's like, 'Kaitlyn, we're not doing a podcast.' And I'm like, 'You forgot to hit record, didn't you?!'" Kaitlyn shared with a laugh.
"He was like, 'No, this is something else,' and he got up and I saw him bring out a ring box from the drawer."
Kaitlyn continued, "I was trying to be present but I was so overwhelmed, and I was so embarrassed, because I was wearing a T-shirt that said, 'Tequila for Breakfast.' I was like, 'This feels very on brand, but also very inappropriate!'"
Jason purchased an oval-diamond of 5.09 carats for his future bride-to-be from a small Canadian business right outside the town where Kaitlyn was born, according to ET.
He added that the business "even took designs from Kaitlyn's dresses, and red carpets, to see what she likes, like working lace in, because she wears a lot of lace. They gave it a Kaitlyn, kind of like an edgy feel, but still classic."
Kaitlyn assured Jason, "I love it, it's perfect. I've been staring at it all day,"
"Luckily I got my nails done the day before," she added, "but these are some funky nails!"
Jason revealed that he originally planned to pop the question during their upcoming trip to Cabo San Lucas, Mexico, where they'll reunite with Kaitlyn's mother -- whom she didn't see in the last year due to the coronavirus pandemic -- and stepfather.
But Jason said he changed his mind and made "a quick adjustment" after thinking about how bringing the ring through customs could complicate things.
"I really did think a Jason way of doing it would have been something extravagant and really big," Kaitlyn explained.
"I actually thought he was going to do it maybe in Mexico, on the beach, and I would have saw it coming. I really wanted it to be intimate, so I loved that it was just during our podcast."
Kaitlyn took to Instagram on Tuesday to share pictures of her ring and captioned the slideshow with Jason, "Don't pinch me."
Jason also gushed of his new fiancee on his own Instagram account, "Choosing your forever is the most important decision in the world. @kaitlynbristowe you made that decision so easy! Love you to death and forever."
Now that the couple is engaged and soon-to-be married, starting a family is definitely in Kaitlyn and Jason's near future.
Kaitlyn told E! News in September 2020 that she was going to be ready to start trying for a baby after her stint on Dancing with the Stars' 28th season, which ended with Kaitlyn and pro dancer Artem Chigvintsev winning the mirrorball trophy.
"I'm going into Dancing with the Stars being like, 'Okay this is my last hurrah,' because I'm ready to have babies," Kaitlyn said at the time, adding, "I really want to feel like I'm in the best shape of my life, to feel strong and to go into a healthy pregnancy."