Stable organic radicals represent a unique type of functional materials for a broad scope of applications in optoelectronic and spintronic devices. A central challenge towards these applications is how to suppress the inter-radical aggregation that often causes aggregation-induced photoluminescence quenching and limits the correlation lifetime of the electron spins from the radicals. Here we report an effective approach to fine-tuning luminescence and spin dynamics using a series of polyester-tethered single radicals, with a common core of carbazole-triphenylmethyl radical but different chains of polyesters with distinct glass transition temperature and rigidity. The rigidity of the polymeric matrices plays a critical role in tuning the luminescence and electron spin resonance of the radicals. The tunable properties of luminescence and electron spin dynamics as well as robust photostability of such polymer-tethered single radicals represent important attributes for cutting-edge applications in optoelectronic devices and quantum information technologies.