Hilton, 26, and her younger sister, Nicky, each chose one finalist for the Miss Universe Japan contest. A dozen or so more will be selected next month.
"I love Tokyo," Hilton said Tuesday. "The shopping is great."
Hilton has promised to improve her bad-girl image since she finished a jail term this June for violating probation in an alcohol-related reckless driving case. She had announced plans to do charity work in Rwanda this month for the Playing for Good Foundation, but the trip was postponed until next year.
Her appearance at a Tokyo fashion boutique to judge the contest packed the room with photographers and TV cameras. Gawking bystanders lined the street outside.
Japan has the reigning Miss Universe, Riyo Mori, the first Japanese to win the pageant since 1959.
Paris Hilton may not be ready for her planned charity work in Rwanda, but she was up for judging a beauty contest in Tokyo.