Charge transport of conjugated polymers in functional devices closely relates to their density of states (DOS) distributions. However, systemic DOS engineering for conjugated polymers is challenging due to the lack of modulated methods and the unclear relationship between DOS and electrical properties. Here, the DOS distribution of conjugated polymers is engineered to enhance their electrical performances. The DOS distributions of polymer films are tailored using three processing solvents with different Hansen solubility parameters. The highest n‐type electrical conductivity (39 ± 3 S cm−1), the highest power factor (63 ± 11 µW m−1 K−2), and the highest Hall mobility (0.14 ± 0.02 cm2 V−1 s−1) of the polymer (FBDPPV‐OEG) are obtained in three films with three various DOS distributions, respectively. Through theoretical and experimental exploration, it is revealed that the carrier concentration and transport property of conjugated polymers can be efficiently controlled by DOS engineering, paving the way for rationally fabricating organic semiconductors. The charge transport properties of conjugated polymers relate closely to their density of states (DOS) distributions. This work enables DOS engineering of conjugated polymer by using different processing solvents to improve three electronic parameters in one polymer system: electrical conductivity, power factor, and Hall mobility. It is suggested that DOS engineering is crucial for the refinement of conjugated polymers for different electrical performances.