The `He`s Just Not That Into You` star - who has been dating actor Joey Kern for almost two years - told friends of plans to wed earlier in the month, and her representative has since confirmed the happy news.
A source told Us Weekly magazine: "Yup, it`s definitely true! Joey emailed all his friends back on the 12th and gave them the good news."
The 32-year-old actress - who previously dated `American Pie` actor Chris Klein - recently admitted she is at her happiest and most productive in her career when she is in love.
She said: "I`m a better person in a relationship, and I`m a happier person. I need to come home at the end of the day and have it not be about me and my hair and make-up.
"And I think my work is more inspired when home is safe and sound and solid because what I do for a living is so bananas and so insecure."