At the Magic Kingdom you can find Mickey in the Town Square Theater on Main Street. In EPCOT he is always at the Character Spot. At Animal Kingdom you can meet him at the Adventurer's Outpost on Discovery Island. In Hollywood Studios Mickey dons his Sorcerer costume from probably his most famous on screen moment from Fantasia.
In Disneyland, Mickey can be met in the Movie Barn in Toontown, and intermittently on Main Street throughout the day. At Disney California Adventure he can be found on Buena Vista Street.
In Disneyland Paris he can be regularly seen all the time at his home on Fantasyland, 'Meet Mickey Mouse'. He can also be found in the Front Lot or Toon Plaza of Walt Disney Studios.
In Tokyo Disneyland Mickey can be found in his house in Toontown or in World Bazaar, and at DisneySea he is at Lost River Delta and American Waterfront.
In Hong Kong Disneyland Mickey meets his fans at Fantasy Gardens, and quite often on Main Street USA, too.
On the Cruise Line, Mickey can be met at selected times in the Atrium Lobby or by the Walt Disney Theater. Check your Personal Navigator for details.