Chmerkovskiy and Smirnoff, who are regulars on the U.S. competition series "Dancing with the Stars," have been a couple for about six months. They are now performing with the "Dancing with the Stars" stage tour.
Smirnoff previously dated actor and television personality Mario Lopez, who had been her celebrity partner on "DWTS" in Season 3.
A source told People Chmerkovskiy proposed to Smirnoff on New Year's Eve in Las Vegas.
"They are really cute together," the insider said.
The dancers' publicists declined to comment on the story, the magazine said.