This chapter deals with the principles of biorefinery and resource recovery as vital elements of sustainable waste utilization. Biorefinery, as a new concept of processing biomass, can serve as an alternative to linear production systems. Biorefinery is a form of biomass processing in which the feedstock can be transformed into a range of useful products such as bioenergy, biochemicals, biopolymers, and biomaterials. This chapter provides key concepts related to feedstock selection, conversion technologies (biochemical, thermochemical, and hybrid processes), product diversification, and waste valorization. An important characteristic of a biorefinery is its interaction with circular economy principles, including waste prevention, resource efficiency, reuse, recycling, and recovery. Closing the loop for waste streams makes biorefinery a vital contribution to transforming biodegradable waste into valuable resources, reducing waste generation. Several case studies of biorefinery projects that were successful in implementing circular economy principles are highlighted in this chapter. These additional strategies involve maximized recovery and valorization from biodegradable waste and consist of the following practices: bioenergy production, biochemical extraction, and material recovery. Innovations regarding processes in biorefineries are further covered by relating them to benefits and payback that this might present to the environment in reducing greenhouse gases and, further, energy and even financial gains. The principles of embracing biorefinery and the circular economy will ensure more effective resource recovery, promote environmental sustainability, and foster economic development. Eventually, this chapter will remind everyone of how crucially important biorefining is for circular bio-economy transition—both concerning waste management issues and the recovery of scarce resources.