In this work, a π-extended acceptor strategy for designing chiral thermally activated delayed fluorescence (TADF)-active materials with highly efficient circularly polarized electroluminescence (CPEL) properties has been proposed. Consequently, three pairs of TADF-active enantiomers based on axially chiral biphenyl skeleton, namely R/S-Ax-CN, R/S-Ax-H, R/S-Ax-OCH3, were designed and constructed. Various para-substituted push–pull electron groups were introduced into the axially chiral skeleton to comprehend the structure–property relationship. Compared with R/S-Ax-H and R/S-Ax-OCH3, R/S-Ax-CN exhibited a higher PLQY of 88.6% and a smaller ΔEST of 0.13 eV, ascribing to the pull electron effect of CN group to make a more delocalized distribution of LUMO orbital and a lesser overlapping of frontier molecular orbitals. Consequently, the CP-OLEDs of R/S-Ax-CN showed a remarkable external quantum efficiency up to 21.0% and 19.7% and intense CPEL signals with the electroluminescent dissymmetry factors (gEL) up to +4.2 × 10−3/−4.4 × 10−3, respectively. This work can provide an efficient and facile way to construct highly efficient CP-OLEDs based on chiral TADF-active emitters by simple molecular engineering of introducing π-extended acceptor.