Herein, three double‐cable conjugated polymers are developed for indoor single‐component organic solar cells (SCOSCs). The new double‐cable conjugated polymers contain pendent nonfused electron acceptors with A‐π‐D‐π‐A configuration, in which group A uses 1H‐indene‐1,3(2H)‐dione (ID) as an electron‐withdrawing end group. The innovative design enables the double‐cable polymer to show absorption spectra in the range of 400–700 nm, which is matched with the spectra of indoor light‐emitting diode lights. In addition, the ID units at the acceptor side units and the introduction of halogen atoms make the double‐cable polymers show high photovoltage (>1.0 V) in SCOSCs. As a result, SCOSCs based on the new double‐cable polymers exhibit a high efficiency of 18% under indoor light illumination. The findings present a novel modular design approach for wide‐bandgap double‐cable conjugated polymers that can be utilized for indoor photovoltaics.