The 37-year-old American dancer and 30-year-old Australian dance pro marked the occasion by dedicating sweet Instagram posts to each other and their 1-month-old son.
"Happy V-Day to my absolute number one. Thank you, I love you and I'm in love with us... #Family #babyChmerkovskiy #HappyValentinesDay," Chmerkovskiy captioned a photo of himself with Murgatroyd and their son.
"To the loves of my life... my one and only Valentine, Papa @maksimc ...I love you and our little Shai more than ever," Murgatroyd added. "This is without a doubt the most special and significant Valentines Day for me #happymom #myeverythings XO."
Chmerkovskiy and Murgatroyd met as pros on the ABC reality competition Dancing with the Stars and got engaged in December 2015. The couple welcomed Shai on Jan. 4 after announcing in June that they were expecting.
"It's been one week plus one day of my fatherhood and I'm the happiest person that's ever lived," Chmerkovskiy told fans in January. "I'm also feeling very protective and now understand what every parent in history have been going through for as long as humans have been giving birth."
The Dancing with the Stars couple stepped out last week for the first time since their son's birth to attend a show at New York Fashion Week. Chmerkovskiy couldn't help but gush about Murgatroyd, calling the new mom the "hottest chick in the spot."