The Flyers chose not to offer Oates a new contract following the loss, making him an unrestricted free agent. He then signed a $3.5 million contract for the 2002–03 season, with an option for 2003–04, with the Mighty Ducks of Anaheim on July 1, 2002. He scored 45 points in 67 games with the Mighty Ducks, and added 13 points in 21 playoff games. Anaheim reached the 2003 Stanley Cup Finals, where in the third game of the series against the New Jersey Devils, Oates assisted on Ruslan Salei's overtime-winning goal. It was Oates' ninth career playoff overtime point, tying him with Joe Sakic and Doug Gilmour for the NHL all-time lead. The Ducks ultimately lost the series in seven games.