The 23-year-old model shared a video with Bieber, 26, as her first post Tuesday.
The clip shows Baldwin and Bieber performing the "Why is Everything Chrome" dance challenge. The video had received over 1.4 million likes as of Wednesday morning.
"we finally joined the tik tok world! we tried," Baldwin captioned the post.
"Obviously this is a really scary time. I wanted to remind everyone what we can do when we come together!! LETS COME TOGETHER BY ISOLATING OURSELVES UNTIL WE HAVE MORE ANSWERS! Our grandparents are counting on us," he wrote.
People reported Tuesday that Baldwin and Bieber have left Los Angeles for Bieber's home country of Canada.
"They plan on socially distancing themselves," a source said. "In Canada, their home is very secluded and they are able to be out in nature still."
"They plan on staying in Canada until it's safe for everyone to resume their regular lives," the insider added.
Bieber and Baldwin married in September 2018, and had a second wedding with family and friends in October. On The Ellen DeGeneres Show this month, Bieber shared how Baldwin planned a romantic surprise for his birthday.