A duplex microstructure consisting of body-centered-cubic (BCC/B2) and face-centered-cubic (FCC) phases was observed after homogenization and recrystallization treatments in Al0.45CoCrFeNi high-entropy alloys (HEAs). The precipitates of BCC phase effectively suppressed the grain growth during recrystallization and annealing, resulting in an ultrafine-grained microstructure. Analysis based on the modified Zener-Smith model and growth kinetics for grain size of the matrix indicate the phase boundaries act as strong obstacle for grain coarsening. This dual phase HEAs exhibit yield strength values varying widely from 300 MPa to 1200 MPa, depending on the heat treatment conditions and corresponding microstructures. An excellent combination of yield strength (~980 MPa), ultimate tensile strength (~1160 MPa), and tensile elongation (~15%) was achieved by optimizing and coupling both phase precipitation and recrystallization kinetics. The current work describes a strategy in developing high-performance ultrafine-grained HEAs for future industrial applications. Display omitted •Fabricating ultrafine-grained dual phase Al0.45CoCrFeNi high-entropy alloys via thermo-mechanical processing•The precipitation of B2 phase effectively suppresses the recrystallization kinetics of matrix.•The strength and ductility of high-entropy alloys were tuned by tailoring the phase precipitation and recrystallization.