Theroux, 41, and Aniston, 43, have known each other for years, but started dating more than a year ago after working on the comedy "Wanderlust." The two moved in together and tabloids soon began predicting everything from marriage to babies for the new couple.
No wedding date was announced.
The marriage will be the second for Aniston, after her first marriage to Brad Pitt ended in divorce in 2005. Pitt broke it off after falling in love with his "Mr and Mrs Smith" co-star Angelina Jolie. Since the infamous divorce, Aniston's love life has been followed unremittingly ever since by the world's celebrity media.
Aniston's previous boyfriends include singer John Mayer and actor Vince Vaughn.
Pitt and Jolie announced their engagement in April but have not publicly set a wedding date.
Aniston rightly deserves happiness and fans all over are pouring in their support for this engagement and marriage to last. Fans have taken to Twitter to congratulate the happy couple. "Jen, I wish you only the best for you. May Theroux be your Happily Ever After!," wrote Hulahob.
