Abstract Circularly polarized luminescent inorganics arouses attentions due to scalable preparation and versatile chiral optoelectronic applications. Here, strong circularly polarized luminescence (CPL) activity has been developed from self‐assembled cellulose nanocrystals decorated with blue emitting silicon quantum dots (QDs). The electrostatic attraction promotes the successful incorporation of QDs into chiral template matrix to form homogeneous hybrid nanoarchitecture films. It is found that their circular dichroism behaviors are closely related to the photonic band gap (PBG) while the CPL behaviors are determined by the QDs and PBG simultaneously. Furthermore, the as‐prepared chiral composite thin films have been employed as an efficient circularly polarized light source for preparing enantioselective polymer, which can induce chirality and photopolymerization simultaneously. Such strong CPL activity in nanoarchitecture films is highly promising for future inorganic optoelectronics.