The Hello Kitty cartoon character is known across Asia
The armband is large, bright pink and has a Hello Kitty motif with two hearts embroidered on it.
From today, officers who are late, park in the wrong place or commit other minor transgressions will have to wear it for several days.
The armband is designed to shame the wearer, police officials said.
"This is to help build discipline. We should not let small offences go unnoticed," Police Colonel Pongpat Chayapan told Reuters news agency.
"Guilty officers will be made to wear the armbands in the office for a few days, with instructions not to disclose their offences. Let people guess what they have done," he said.
Further offences would be dealt with using a more traditional disciplinary panel, he said.
The cartoon character Hello Kitty was first introduced by Japanese company Sanrio in 1974.The cute round-faced cat has become an Asia-wide marketing phenomenon, with Hello Kitty products such as stationery, hair accessories and kitchen appliances available across the region.