The YouTuber, 26, popped the question to girlfriend Thea Booysen, 27, on Christmas Day at their home surrounded by their families, who were in on the surprise.

"My family flew out from South Africa for Christmas and we were going to do Christmas in our house so both families were here. We were opening presents, and then for the very last present he asked me to close my eyes because it was a surprise," Booysen exclusively tells PEOPLE.

"I intentionally dropped a large box to make noise before presenting the real gift — with the ring inside — to her. And then I went down on a knee and proposed," says MrBeast (born Jimmy Donaldson).

After Booysen opened her eyes, she "of course said yes" and was "extremely excited."

"I was trying to think of the best way to catch her off guard so it would be a surprise," Mr Beast continues. "Thea is really close to her family, so I wanted to make sure that they were included in this momentous occasion. Christmas worked out great because they were in town from the other side of the world."

Even though the social media star is known for his elaborate challenges and large-scale stunts, he wanted his engagement to be small and special.

"My friends thought I would want to propose in a very public way, like some sort of spectacle at the Super Bowl or somewhere else really big like that, but I knew that I wanted it to be the opposite, to be really private and intimate," he says.

Although the bride-to-be "would have been happy with a plastic ring," MrBeast proposed with a "beautiful" diamond on a rose gold band with additional diamonds on each side.

MrBeast met Booysen, a fellow gamer and internet personality from South Africa, in 2022 when he was visiting her home country. During the trip, MrBeast went to dinner with a mutual friend who invited Booysen to join them.

"When I met him, I was quite surprised how down-to-earth he was, and also how intelligent he was," Booysen recalls. "I thought YouTubers were just sort of a persona, but when I met him, I was quite surprised to see that he's actually a nice guy. He wasn't sitting there with an ego."

The two quickly bonded over their passion for learning and got into a deep conversation about science, YouTube and beyond.

"When we were first introduced, it came through right away how brilliant Thea is," MrBeast tells PEOPLE. "She has such a range of knowledge and can go deep on lots of topics. She told me about her work as an author and how passionate she is about her hobbies — we vibed instantly. I kept thinking she is really smart and beautiful. I knew within the first few minutes of meeting that I wanted the chance to date her. Thankfully, she also felt a strong connection."

While it's true that Booysen felt a connection, she thought it would end there as MrBeast was going back to the United States.

"When I got home I was a little bit flustered, and I must say I thought he was really cute, but I thought that was the end of it," says Booysen, whose first serious relationship was with her now-fiancé.

Not long after, she opened her DMs on X (formerly Twitter) and saw a message from MrBeast. He asked if he could read the book she was writing at the time, The Marked Children, when it was finished. Not realizing he was flirting, Booysen didn't connect with MrBeast until more than a month later when her book was written.

The two jumped on a three-hour call together, and the rest is history.

"Then I knew [he was the one]," she says. "I fell in love with his brain. To me [that's] everything — your brain, your drive, your discipline, your character, that's everything to me. So after that, he immediately planned to come back to South Africa to meet up with me this time, and we started dating the moment he arrived."

The couple made their first public appearance at the Kids’ Choice Awards in April 2022, with Booysen later describing it as an “amazing night" on Instagram.

The following year, MrBeast told Booysen of his plans to propose. Before she headed to the United Kingdom to get her master's degree, he asked her when would be a good time to pop the question. She responded that he should do so after graduation.

MrBeast ultimately proposed one month after Booysen graduated with a master's degree in human cognitive neuropsychology at the University of Edinburgh. She also has a bachelor's degree in law and an honors degree in psychology.

For Booysen, marriage is "just a formality" because she and MrBeast already act like they're married.

"In my mind, we're already married. We're already on the same page about these things. We talk about children, how we're going to live together when we're 70 years old… this was just another step in the process," she says.

Even though MrBeast's schedule is packed, Booysen says they have great support for wedding planning.

"We have the best team, I want to say in the world, who can quickly plan a wedding if we need to," she says.

MrBeast has amassed more than 340 million subscribers on YouTube since 2012 and is considered one of the highest-paid content creators, but he doesn't want his big day to be in the spotlight.

"This will definitely be more family and friends — definitely more private," the groom-to-be says of his future nuptials. "I don’t take much vacation because of how hard I work, so I definitely want to make sure that the wedding will be a time to celebrate with her and spend time with friends and family who we really enjoy being with. It will be the ultimate way to take some time away and enjoy things."

Booysen adds that they're thinking of saying "I do" on an island.

"We're thinking of doing it somewhere on an island where we're far away from just about everybody," she tells PEOPLE. "We're not going to try and have a big, extravagant wedding. It's going to be nice, but it's certainly going to be intimate [with] close family and friends."

MrBeast often keeps his personal life private but has posted about his relationship with Booysen on social media.

On Dec. 21, the internet star shared a snap of himself and Booysen on Instagram at a red carpet event for his Beast Games reality competition show on Prime Video.

Booysen posted pics from the same night and expressed her admiration for her partner. "Watch BEAST GAMES on Amazon Prime now! I'm so proud of you Jimmy!!" she captioned her post.

The couple seemingly started off 2024 with a vacation to Necker Island in the Caribbean. In January, Booysen uploaded a few behind-the-scenes photos of the pair enjoying their relaxing getaway.

One of the photos features the two sitting in a lounge area by a pool with games of checkers and chess set up, while another shows MrBeast holding a beverage to Booysen’s face as she’s covered in two blue blankets and wearing sunglasses and a fashionable sailor hat.

Wherever he is, MrBeast's favorite part of his day is spending it with Booysen.

"After working 14-15 hour days, I  just want to chill and hang out — and Thea loves doing a lot of the same things that I do," he says. "We have a lot of similar interests — playing video games, spending time with our dogs and seeing the world. We also watch random shows, but we also like learning from different types of educational shows."

Now, the pair are looking forward to life as husband and wife.