Highly versatile BODIPY dyes proved themselves to be very useful as photosensitizers. These dyes can be derivatized to absorb essentially anywhere in the visible the near IR region of the spectrum. As a result of their diverse reactivity, singlet oxygen generation efficiency can be modulated very precisely, leading to a number of selective photosensitizers for photodynamic therapy. Among the biologically relevant modulators, glutathione concentration and pH received particular attention. In this review, we highlight modulatable BODIPY-based photodynamic photosensitizers, and various synthetically useful chemical reactions triggered by singlet oxygen and other reactive oxygen species generated by BODIPY-based photosensitizers.