The vast amount of biological mysteries and biomedical challenges faced by humans provide a prominent drive for seamlessly merging electronics with biological living systems (e.g., human bodies) to achieve long-term stable functions. Towards this trend, one of the key requirements for electronics is to possess biomimetic form factors in various aspects for achieving diverse functions and long-term stability. To enable such paradigm-shifting requirements, polymer-based electronics are uniquely promising for combining advanced electronic functionalities with biomimetic properties. In this talk, I will introduce our design concepts for semiconducting polymers, which enable the incorporation of various biomimetic properties. First, I will introduce a new design strategy for introducing bioadhesive properties to redox-active semiconducting polymers, so as to enable intimate and stable interfacing of transistor-based biosensors with tissue surfaces. Second, to solve the issue of immune reactions and foreign-body responses to implantable bioelectronics, I will discuss our recent exploration of studying and developing immune-compatible and ultrasoft hydrogel designs for polymer semiconductors and conductors. Finally, I will show our design of stretchable light-emitting polymers with high quantum efficiency, which is enabled by the use of thermally activated delayed fluorescence. Collectively, our research is opening up a new generation of electronic materials that fundamentally change the way that humans interact with electronics.