The gold medalist and her husband Andrew East made their announcement across various social media platforms on Thursday and even set up an Instagram account for their baby.
“@theeastbaby ... we cannot WAIT to welcome you to the world and shower you with love. @andrewdeast WE DID IT!” Johnson posted on Instagram.
East, a football player for the Washington Redskins, posted a short video with Johnson on Twitter saying, “Coming 2019.”
The couple also posted a video on YouTube that they had filmed in February after they first found out Johnson was pregnant.
The 27-year-old Olympian expressed how she felt about being pregnant again after her miscarriage in October 2017.
“I’ve never really voiced any hesitation with trying again, but yeah, I’m absolutely terrified,” she said in the video.
“It’s natural for anybody who’s experienced pain or loss to guard their hearts when things happen again. So I can naturally feel that my heart is just guarding itself. ‘Cause I don’t want to go through that again,” she continued, adding later: “I hope I’m able to let that guard down a little bit.”
At the time of Johnson's miscarriage, she and East posted a video about the experience.
"The past 48 hours have been some of the happiest, scariest, and saddest times of my life," Johnson wrote in the caption of the video. "My husband Andrew and I found out that we were unexpectedly pregnant, only to find out hours later some tragic news. I have been crying more than I ever have, but am still optimistic for what is next."
Several days later, the couple released a follow-up video thanking fans for the “outpouring of support.”
Johnson and East were married in April 2016.