After dating for just over a year, the pair plan to walk down the aisle, Theroux's rep confirmed to People: "Justin Theroux had an amazing birthday on Friday, receiving an extraordinary gift when his girlfriend, Jennifer Aniston, accepted his proposal of marriage."
Aniston's rep also confirmed to The Huffington Post that she is, in fact, engaged.
The couple began dating in May 2011, before going on to co-star in the 2012 comedy, "Wanderlust." Since then, Aniston and Theroux have been almost inseparable -- they've even begun to look like one another as their relationship has evolved.
Last month, the pair were spotted vacationing in the romantic city of lights, fueling rumors that Paris could be the setting for Theroux, 41, to pop the question. But it turns out he would wait until August 10.
Aniston, 43, was previously married to Brad Pitt. This will be Theroux's first marriage.
News of Aniston and Theroux's engagement comes on the heels of Friday's speculation that her ex and Angelina Jolie would be getting married this weekend at the couple's French chateau, but almost as quickly as they started, the rumors were laid to rest.
CORRECTION: In a previous version of this story, it was the said that Aniston and Theroux were vacationing in Hawaii in August 2012. Their Hawaiian getaway was actually the year before. Changes are reflected above.