"I was just cast in my first feature film comedy! I start filming monday!!!!!" Montag tweeted. "This is one of the best days of my life!!! Getting icecream to celebrate!"
"The Hills" starlet will be making a cameo in the 2011 Adam Sandler comedy "Just Go With It," alongside Jennifer Aniston and Nicole Kidman.
Montag later tweeted, "Memorizing my script for the feature comedy movie I am filming all next week."
The reality star recently gave husband Spencer Pratt the boot and hired a psychic to guide her career.