Jaime Pressly did not have her burglar alarm on when burglars hit Friday night, and they made off with $30k in jewelry ... TMZ has learned.
We broke the story ... Jaime was the latest celeb to be hit in L.A. -- other victims include Kendall Jenner, Yasiel Puig and Alanis Morissette.
The thieves got in by breaking a window, but we're told the security company never called the cops and therefore they believe the alarm wasn't on.
Jaime discovered the burglary when she returned home after an evening out.
In addition to the jewelry, the crooks also took her laptop.