Nonviral gene delivery vectors need to overcome both extracellular and intracellular obstacles before releasing plasmid DNA in the transcriptionally active form. However, serum and transport stability desired for cationic polymer/pDNA polyplexes contradicts with the eventual plasmid release requirement; chain lengths of cationic polymer vectors render additional compromise between cytotoxicity and transfection efficiency. Although the introduction of stimuli-triggered degradable cationic polymers can partially solve these issues, the quest for novel design criteria and elucidation of elementary cellular transport pathways are highly desirable. Herein we report a supramolecular approach to construct fluorogenic gene delivery vectors via self-assembly of intracellular milieu-reactive cationic amphiphiles. This new type of micellar nanocarriers can effectively bind pDNA to form polyplexes due to multivalent cationic segments at micellar coronas. Upon cellular uptake and endosomal escape, hydrophobic micellar cores are subjected to fluorogenic Michael addition reactions with highly hydrophilic cytoplasmic thiols, leading to micellar disintegration, pDNA release, and emission turn-on for image-guided delivery.