The molecular properties of semiconducting polymers with regioisomeric structural factors can be effectively tuned based on their regiochemistry. Thus, the molecular dynamics, intermolecular stacking, and film morphology of these polymers have been tuned via regiochemical control to ultimately enhance their electronic properties in organic field-effect transistors (OFETs). This strategy can also be employed to induce high deformability in organic electronics. In this review, studies on the regiochemistry of conjugated polymers based on the dimensions of regiochemical factors and synthesis methods are summarized to enable the control of the regiochemistry of substituents, side chains, and backbone linkages that can impact their optoelectronic properties and solid-state morphologies. Moreover, technological developments in the fabrication of OFETs with highly enhanced mobility toward stretchable electronics have been discussed.