Yes, She was once some CEO's administrative assistant before he tried to have her killed.(movie version) Not sure how close it followed the comic storyline.

As Frank Miller explained in "Batman, year one",Selyna Kile was a prostitute. Nowadays she´s a full-time thief.

Apparently, she started off as a prostitute in the comics. But the movies didn't want to show that to kids. In Batman returns, she's a secretary for a corrupt industrialist named Max Shreck (fictional character, not from the comics) and when he found out she had been reading through his files, he pushed her out of a window and she fell several stories and died in an alley. There, she was revived by a group of cats who licked her wounds, and she found she had martial arts and acrobatic skills, as well as accuracy with a whip. By day she carried on being Selena Kyle but by night she donned her sexy cat costume to exact revenge against Max Shreck. In Batman the Animated Series, it is not known how or why Selena became Catwoman, just that she is an animal rights activist and she steals jewels as Catwoman so she can earn the money to support endangered animals, particularly wild cats. In the Halle Berry version, she dosn't live in Gotham City and isn't even named Selena Kyle (it's Patience something) but she starts off as a graphic designer who is drowned by her boss' hench men. She is then resurrected by a rare Egyptian Cat who endows her with a cat's senses to live outside of society and take her own kind of justice against corrupt villains.