Betty White hit 95 today and she's still going strong, doing what she's best known for ... working her butt off in Hollywood.

Sources close to Betty tell TMZ ... she's preparing for a guest spot on the sitcom "Young & Hungry" on Freeform TV. So, instead of relaxing on her bday, we're told she's doing a table read and running around on set. Impressive.

As for Tuesday night, our sources say Betty has very low-key plans ... just a small get-together with friends. We're jealous of those friends.

Happy birthday, golden girl!