Self-assembly of amphiphilic polymers in aqueous solution builds up versatile carrier platforms for therapeutic delivery. Amphiphilic polymers specifically provide "hydrophobic pockets" for the encapsulation of water-insoluble small-molecule drugs, along with effective strategies to control the cargo release. Random and block copolymers have been separately demonstrated to affect the cargo encapsulation and release. In this study, we present self-assembled structures of blended random and block copolymers to tune the encapsulation and release of lipophilic cargo molecules. The hydrophilic-lipophilic balance (HLB) within the polymeric (co-) assemblies greatly affects their cargo loading capacity. Meanwhile, the disulfide moieties within the polymeric assemblies allow controlled cargo release upon a redox stimulus such as glutathione. The triggered release of encapsulated cargos is affected by the overall HLB, the reactivity, and accessibility of the disulfide species within the polymeric assemblies.