The Shameless star and the writer/director became engaged over the weekend in Los Angeles, PEOPLE has learned exclusively. Rossum, 28, and Esmail, 37, have been dating for two years.
The happy personal news adds to what has been quite a year professionally for the couple, with Rossum's turn as Fiona on Showtime's Shameless continuing to earn her acclaim, and Esmail's work as the creator of USA's buzzy drama Mr. Robot making it a breakout year for him.
Esmail directed his bride-to-be in his 2014 romantic dramedy Comet, which also starred Justin Long.
Last year, Rossum painted a sweet picture of her then-boyfriend Esmail, telling PEOPLE he indulged the actress for her 28th birthday by allowing her to have a female-centered celebration.
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"We went to the opera and saw Traviata. And then we had a dinner party at my house. It was nine girls and my boyfriend," Rossum said. "Poor thing, or lucky him."