The couple announced in December that they were expecting twins.
Luyendyk and Burnham, who announced they were expecting twins in December, are already parents to 1-year-old daughter Alessi.
"BOY! & GIRL!" Luyendyk captioned a series of photos of himself and Burnham posing with their 1-year-old daughter Alessi and pink and blue cotton candy. "How did we get so lucky @laurenluyendyk?! So excited to meet the @luyendyktwins ❤️❤️Photos: @griffithimaging."
Burnham wrote alongside her post, "Alessi is getting a baby BROTHER & a baby SISTER💙💗 we couldn’t be more excited! 📸: @griffithimaging."
The couple shared the moment they found out in a video on their YouTube channel. Burnham shared that while picking up the results, her doctor informed her that the gender is more of a prediction with twins before confirming with an ultrasound.
"My prediction, I think we are either having a boy and a girl, or two boys. But after that conversation with her just now, maybe it says there's two girls. But I still think there's a boy in there," Burnham said.
"My mind is still blown on how she said it might not be accurate, because there's either a Y chromosome, or there's not. So you either know you at least have one boy, or they're both girls," Luyendyk replied.
The pair couldn't have been more excited to discover they were expecting a boy and girl.
See more on the couple in the video below.