Earlier in the day, Lohan sizzled in a plunging one-piece, showing off her swimsuit bod.
The 29-year-old actress wore another deep plunging number on April 12 when she joined her father Michael and mother Dina at the Duran Duran concert at the Barclays Center in Brooklyn, New York. Earlier that same day, ET confirmed Lohan's engagement news.
Michael spoke to ET shortly after, gushing about his daughter's relationship.
"I'm so happy that Lindsay has found true happiness," Michael told ET. "It's written all over both of them."
The Mean Girls star and the 22-year-old Russian business heir have been dating for less than a year, and the actress only confirmed their relationship in March, gushing to The Sun, "I do have a boyfriend and he is a great guy."