<p>By using flexible and stretchable materials in place of fixed components, soft robots can materially adapt or change to their environment, providing built-in safeties for robotic operation around humans or fragile, delicate objects. And yet, building a robot out of only soft and flexible materials can be a significant challenge depending on the tasks that the robot needs to perform, for example if the robot were to need to exert higher forces (even temporarily) or self-report its current state (as it deforms unexpectedly around external objects). Thus, the appeal of multifunctional materials for soft robots, wherein the materials used to build the body of the robot also provide actuation, sensing, or even simply electrical connections, all while maintaining the original vision of environmental adaptability or safe interactions. Multifunctional material systems are explored throughout the body of this dissertation in three ways: (1) Sensor integration into high strain actuators for state estimation and closed-loop control. (2) Simplified control of multifunctional material systems by enabling multiple functions through a single input stimulus (<i>i.e.</i>, only requiring one source of input power). (3) Presenting a solution for the open challenge of controlling both well established and newly developed thermally-responsive soft robotic materials through an on-body, high strain, uniform, Joule-heating energy source. Notably, these explorations are not isolated from each other as, for example, work towards creating a new material for thermal control also facilitated embedded sensory feedback. The work presented in this dissertation paves a way forward for multifunctional material integration, towards the end-goal of full-functioning soft robots, as well as (more broadly) design methodologies for other safety-forward or adaptability-forward technologies.</p>