The fabrication of reactive aggregation nanomaterials through assemblies in a facile and cost-effective manner is much desired but remains to be well explored. Here we show that exquisite and ultra-long (>2 μm) hybrid polymer nanorods (NRs) can be formed by a simple self-assembly of a phenylboronic acid modified genistein crosslinker (Ge-di(HMPBA-pin)) and D-α-tocopheryl polyethylene glycol 1000 (TPGS). The obtained NRs exhibit quantitative and sensitive colorimetric detection of H₂O₂ with a remarkable detection limit for different stromal materials. More significantly, the presence of H₂O₂ triggers a distinct morphological transformation of the polymer NR assembly into the secondary structure of micelles via the oxidative deboronation of boronate moieties in HMPBA-pin-SA. It spontaneously induces the aggregation of metal nanoparticles (Au NPs), metal nanorods (Au NRs), quantum dots (MoS₂ QDs), metal ions (Cu²⁺), protein (ferritin) and tetraphenylethene (TPE) molecules, giving rise to a dramatic stimuli-triggered open/close switchable complexation and apparent colorimetric transitions in vitro. This study, for the first time, showcases the fascinating advantages of such unprecedented secondary structure-induced aggregation and uncovers the immense potential to design a plethora of other sensing systems by virtue of the alternate trigger-specific, sacrifice-aggregated building moieties.