The Mean Girls star rocked a casual black-and-white Temperley dress with black Superga UK platform sneakers, while Tarabasov donned a white T-shirt and denim jacket. Lohan also posed for photos with her beau, fashion designer Alice Temperley, who was hosting the event, as well as photographer Greg Williams.
Earlier in the day, the couple had lunch to celebrate Tarbasov's 23rd birthday, with Lohan giddily documenting the occasion on Instagram. "Rushing around from work to lunch to work and fittings but still smiling!!" she wrote.
Despite dating for several months, the two never officially announced their engagement, but LiLo was spotted rocking what appeared to be an engagement ring at a Duran Duran concert in Brooklyn on April 12. That same day, ET confirmed the engagement news.