Spent coffee ground, poultry manure, and agricultural waste-derived biochar were used to manufacture functional composts by bioaugmentation of microorganisms. The highest biochar yield (40.7%) was obtained at 450oC with the surface area (2.35 m2/g). Four pilot scale composting reactors were established to perform the composting for 45 days. The ratios of NH4+-N/NO3--N as an indicator of compost maturity in the composts TR-2, TR-3 and TR-L were significantly lower compared with TR-1, indicating a rapid and successful composting via microbial bioaugmentation and biochar amendment. Moreover, germination indices for radish also increased by 14 -34% through the augmentation and biochar amendment, indicating their positive impacts on manufacturing of mature and functional composts. The microbial diversity was also enhanced in the augmented and biochar-amended composts by 7.1-8.9%, where two species of Sphingobacteriaceae were dominant (29-43%). TR-2 and TR-3 enhanced DPPH scavenging activity in pepper leaves by 5.9% and 13.3%, respectively compared with TR-1 in a field study while the scavenging activity in fruit by 14.1% and 8.6%. TR-3 also enhanced total phenolic content in pepper fruit by 68%. Moreover, the composts TR-L and TR-L(2x) boosted DPPH scavenging activity in leek by 111% and 72%, respectively, compared with the commercial organic fertilizer while TR-1 and TR-3 increased the content by 33.9% and 44.8%, respectively. This implies that a composting facilitated by the microbial augmentation and biochar amendment could shorten the composting time and enhance the quality of functional compost that could better compete with the commercially available fertilizers, and render an eco-friendly recycling of organic wastes such as spent coffee ground, poultry manure, and agricultural wastes.