Mary-Louise Parker's Nanny Allegedly Jacked More Than $30k

12:01 PM PT -- Law enforcement sources tell us the nanny made off with $36,820 from Parker ... with around $15,000 of that coming just from withdraws at a local CVS. Parker caught on to her nanny after her bank alerted her to "possible fraudulent transactions."

Mary-Louise Parker's nanny may have taken some serious liberties with the "Weeds" star's debit card ... allegedly stealing more than $30k when she was supposed to be shopping for the kids.

The nanny, Amanda Hoston-St. Louis, was arrested Monday after cops say she illegally withdrew more than $3k from Parker's account twice in April. The nanny allegedly had access to the star's debit card and PIN number.

Parker's bank notified her about the transactions ... prompting cops to investigate.

Cops say it wasn't the first time the nanny dipped into Parker's account -- she's allegedly been making withdrawals since 2016 ... totaling more than $30k ... as first reported by the NY Daily News.