Abstract Composting is an adequate method for treating and valorizing agricultural waste such as those from Spring onions (SO) cultivation and chicken breeding (chicken manure -CM). However, the low content of Total Organic Carbon in the waste from SO and the high concentration of total nitrogen in CM are limitations for the composting process. This research studied the co-composting of SO and CM in a paramo ecosystem, together with locally available co-substrates such as biowaste (Bw) and woodchips (Wc), focusing on the effect of co-composting in process development and end-product quality. A pilot-scale experiment was carried out using three treatments in triplicated composting piles: i) Treatment A: 43%CM+41%Bw+16%Wc (dry weight); ii) Treatment B: 52%CM+ 32%SO+16%Wc (dry weight), and iii) Treatment C: 70%SO + 30%Wc (dry weight). Treatments A and B reached thermophilic temperatures after two days of the process start and remained at that level for 17 days. However, treatment B reached environmental temperature during curing in a shorter time (43 days) than treatment A (53 days). Treatment C did not achieve thermophilic temperatures. Tests carried out at the end of the process showed end-product stability and non-phytotoxic characteristics (germination indexes 80%). From the perspective of agricultural use, products from the three treatments had limitations due to deficiencies in essential nutrients like phosphorus. Still, they had potential as a soil amendment for restoration processes. The fertility index of the products showed that treatments A and B presented values of 4.3 (over 5.0) while treatment C obtained a value of 2.5.