Intruder Walks into Jennifer Lawrence's Home, Arrested

Jennifer Lawrence got a rude awakening to cap off her weekend -- cops say a female intruder sauntered right into her crib ... and the way she did it was too damn easy.

Law enforcement sources tell TMZ ... a woman entered JLaw's L.A.-area home Sunday around 9:15 PM PT. We're told the woman was totally unexpected, but still ... went right through the front doors, which were NOT locked.

Even more frightening ... our sources say Jennifer was actually home at the time of the break-in -- unclear if her new hubby, Cooke Maroney, was there ... but JLaw's hired muscle certainly was.

We're told security on hand nabbed the 23-year-old woman before she could make contact with Jennifer. They called the police and the woman was arrested for misdemeanor trespassing. As for why she was there?