A new and distinct cultivar of Azalea plant named `Tiara`, characterized by its dark green-colored leaves that do not abscise during the cooling and forcing periods; uniform and outwardly spreading plant habit; freely branching habit; uniform and freely flowering habit; relatively rapid flowering response; large white-colored flowers; semi-double to double flower form; and excellent postproduction longevity with plants maintaining good flower substance for about five weeks in an interior environment.