Police Colonel Pongpat Chayaphan, the acting chief of the Crime Suppression Division in the capital, said senior officers had to resort to such a move as a deterrent.
"Simple warnings no longer work. This new twist is expected to make them feel guilt and shame and prevent them from repeating the offence, no matter how minor," he said.
"[Hello] Kitty is a cute icon for young girls. It's not something macho police officers want covering their biceps."
Pongpat said police caught breaking the law will be subject to the same fines and penalties as the public.
"We want to make sure that we do not condone small offences," he added.
Hello Kitty has been popular for years with children and young women, including pop stars and Hollywood celebrities.
The celebrity cat adorns everything from diamond-studded jewellery, Fender guitars and digital cameras to lunch boxes, T-shirts and stationery.