The Dancing with the Stars pros were joined by several of their castmates (both pros and stars) from the reality competition show in New York City over the weekend for a masquerade-themed celebration at the Diamond Horseshoe club near Times Square.
Murgatroyd, 29, looked the perfect bride-to-be in a white, sleeveless tuxedo-style top with a half skirt. She paired the look with t-strap pumps and lace and mesh leggings.
Chmerkovskiy, 36, looked dapper in an all black suit with a matching tuxedo shirt.
VIDEO: Maksim Chmerkovskiy and Peta Murgatroyd's Love Story – All About the Dancing with the Stars Duo's Surprise Engagement
Rumer Willis, Chmerkovskiy's brother Val's partner on the dancing show, was also in attendance, sharing several photos from the evening.
"What an incredible night celebrating these two," she wrote of a group shot with Sharna Burgess, Tony Dovolani, Val, Murgatroyd, Chmerkovskiy and Nicole Volynets. "@maksimc and @petamurgatroyd I am so honored to have been apart of it. Love you both."
Burgess also took to Instagram after the celebration, posting a photo with Murgatroyd.
"Hugs and endless love for the most beautiful girl in the room, inside and out, every time," the 30-year-old wrote. "What an incredible night baby girl, and it's just the beginning of a new incredible chapter in your life. Love you beyond @petamurgatroyd #bestengagementpartyever."
Murgatroyd and Chmerkovskiy got engaged in December during a performance in Miami. The couple have been dating on and off since 2012.
The pair has not set a date yet, but said in January that they want to do "an East Coast wedding."