This mini-review discusses the progress made in the development of polymerized small-molecule acceptors (PSMAs) for use in all-polymer solar cells (all-PSCs). These PSMAs combine the advantages of both small-molecule acceptors (SMAs) and polymers. Various studies have been conducted using different building blocks to synthesize these acceptors, including indacenodithiophene and indacenodithienothiophene. They exhibit many advantages such as strong absorption in the near infrared region, high electron mobility, and appropriate energy levels, making them good candidate for PSAMs. The improved efficiency of all-PSCs is attributed to several factors, including stronger absorption, improved blend morphology, and redistribution of composition in the film. Additionally, new materials have been incorporated as third components in ternary organic photovoltaics, with some achieving high power conversion efficiencies of up to 17.0%. The development of new acceptors with different building blocks has resulted in improved stability and reproducibility in all-PSCs, paving the way toward high-performance and stable devices. Overall, these developments demonstrate significant potential for further advancements in the field.