A source tells ET that the expecting parents have known the genders of their babies for a while, but were excited to share the news with their friends and fans.
The source adds that Johnson is not nervous about becoming a mother, but is more excited about meeting the babies. When it comes to preparing for their arrival, the couple is all set with a beautiful nursery and Johnson's mother will be coming from Australia to help out with the little ones.
"We're so excited to finally share with everyone that we are having a boy and a girl! #twins #genderreveal #bestofbothworlds," the 41-year-old former Dancing With the Stars pro wrote on Instagram alongside a Boomerang of the reveal. In the clip, she's wearing a gorgeous white ruffled maxi dress, while Herjavec is casually dressed in jeans and a pink button-up.
Johnson also posted a video on her Instagram Story of the moment they revealed the gender of their twins. She also thanked Burke for the adorable cakes, and showed off her pink and blue floral arrangements.
Meanwhile, Burke couldn't help but gush about Johnson, writing on Instagram, "Love showering this beautiful mama-to-be today 💕."
Herjavec and Johnson met in 2015 when they were partnered on DWTS and tied the knot in July 2016. This will be baby No. 1 and 2 for Johnson, while Herjavec is already dad to three kids from his previous marriage to Diane Plese: daughters Caprice and Skye, and son Brendan.
ET caught up with Johnson last month, where she shared the advice that fellow DWTS mom Peta Murgatroyd gave her. Watch below to hear what she said.