Abstract Intrinsically stretchable polymer semiconductors (IS‐PSCs) exhibiting simultaneously high charge‐carrier mobility and robust mechanical properties are highly desired yet remain challenging for wearable electronics. Herein, a conjugated non‐aromatic stacking‐inhibiting ( CNASI ) design strategy is proposed by randomly embedding dithienyl‐dimethylcyclopentadiene (2TCp) units into a diketopyrrolopyrrole (DPP)‐based polymer backbone, obtaining a series of near‐linear and fully conjugated terpolymers containing different contents of 2TCp. Specifically, the geminal dimethyl substituents of 2TCp can introduce steric hindrance into the polymer backbone, effectively suppressing tight intermolecular π – π stacking interactions, while enhancing backbone conjugation and planarity owing to the introduction of a non‐aromatic polyene character. Finally, the optimized 2TCp‐15% terpolymer exhibits a high crack onset strain up to 160%, showing an over‐threefold improvement compared to the pristine PDPPT polymer. Moreover, it exhibits an improved initial charge‐carrier mobility ( µ m ax = 1.32 cm 2 V −1 s −1 ), together with excellent mobility retention and cyclic stability under mechanical strain, compared to PDPPT and a fully aromatic terthiophene‐based reference polymer. This study indicates that subtle modulation of interchain π–π interactions and backbone aromaticity via the novel CNASI strategy effectively balances the trade‐off between mechanical stretchability and electrical performance, providing a new approach for designing IS‐PSCs.