Clinical　diagnostics　and　therapeutics　of　tumors　are　significantly　benefitted　by　the　development　of　multifunctional　theranostic　agents,　which　integrate　tumor　targeting,　imaging,　and　therapeutics.　However,　the　integration　of　imaging　and　therapy　functionalities　to　a　unimolecular　framework　remains　a　great　challenge.　Herein,　a　family　of　amphiphilic　gemini　iridium(III)　complexes　(GIC),　Ir1-Ir6,　are　synthesized　and　characterized.　The　presence　of　quaternary　ammonium　(QA)　groups　endows　GIC　with　adjustable　water　solubility　and　excellent　self-assembly　properties.　Spectroscopic　and　computational　results　reveal　that　introducing　QA　groups　into　cyclometalating　ligands　(ĈN　ligands)　can　overcome　the　drawback　of　aggregation-caused　emission　quenching　and　ensure　Ir1-Ir3　with　high　emission　intensity　and　excellent　singlet　oxygen　(　1　O　2　)　generation　ability　in　aqueous　media.　Cell-based　assays　indicate　that　Ir3　shows　higher　cellular　uptake　efficiency　and　localizes　specifically　in　the　mitochondria,　as　well　as　exhibits　outstanding　photostability　and　an　impressive　phototoxicity　index　with　satisfactory　performance　in　mitochondria-targeted　imaging　and　photodynamic　therapy　(PDT)　of　tumor　cells.　Furthermore,　in　vivo　studies　further　prove　that　Ir3　possesses　excellent　antitumor　activity　and　remarkably　inhibits　the　growth　of　the　HepG2　cells　under　PDT　treatment.　Consequently,　this　study　presents　a　promising　strategy　for　designing　clinical　application　potential　multifunctional　iridium　complex　theranostic　agents　for　mitochondria-targeted　imaging　and　PDT　in　a　single　molecular　framework.　©　2019　American　Chemical　Society.