The biggest tween pop star in the world is so big ... she's gigging at law firms.

Miley Cyrus will be the main attraction at the Lanier Law Firm's "Christmas Cheers and Charity" party next month, reports the Houston Chronicle, where she could be getting upwards of $250K to play for the JDs and their families. They're expecting seven to eight thousand people, or about a tenth of her usual audience.

The invite for the party is pimping "Texas Bar-B-Q, fajitas and amusements." So much for Miley.