Acting as an extracellular matrix protein receptor, alpha(v)beta(3) integrin becomes an appealing target for photodynamic therapy of bladder cancer. Here, specific alpha(v)beta(3)-integrin-targeting porphyrinato-gadolinium complexes (Gd-PEG-R-n) are demonstrated as off-on theranostic agents, where R-n are specific peptides. Among them, Gd-PEG-R-3 shows both impressive phototherapeutic index and robust in vivo magnetic resonance imaging (MRI) signal enhancement. Significant selectivity of Gd-PEG-R-3 is proven by its high alpha(v)beta(3) integrin binding affinity in positive bladder cancer cells. All these findings support Gd-PEG-R-3 as a promising bi-functional medical agent with both MRI contrasting ability and photodynamic therapeutic potential for curing bladder cancer.