Perry launched her first headlining concert tour, the Hello Katy Tour, in January 2009.
On January 19, 2009, Katy Perry launched her debut headlining concert tour, the Hello Katy Tour, in support of her breakthrough album One of the Boys. The tour marked her transition from opening act and supporting artist to a bona fide headlining pop star capable of drawing audiences on her own merits.
The tour spanned multiple continents, including stops in Europe, North America, Australia, and Asia, reflecting the international breadth of Perry's growing fan base following the global success of "I Kissed a Girl" and "Hot n Cold."
This tour was significant not only as a commercial venture but as a proving ground for Perry's live performance identity—incorporating theatrical staging, colorful visuals, and audience interaction that would become hallmarks of her later, larger arena and stadium tours.
The Hello Katy Tour's success helped establish the infrastructure and fan loyalty that would support Perry's subsequent, much larger tours, including the California Dreams Tour and Prismatic World Tour, cementing her reputation as one of pop music's most dynamic live performers.