Bio-based organic acids are an eco-friendly alternative to petroleum-derived products. In this work, the production of organic chemicals was investigated for the first time in the Cosenzaea myxofaciens species using hydrolysed lignocellulosic biomass from Arundo donax. The strain C. myxofaciens BPM1, isolated from bovine rumen, was able to produce a high amount of lactic acid, followed by acetic and succinic acids in synthetic substrate in microaerophilic and anaerobic conditions. When hydrolysed lignocellulosic biomass from Arundo donax supplemented with several nitrogen sources was used as substrate in separate hydrolysis and fermentation in anaerobic conditions, a significant increase in organic acids was recovered, reaching values up to 12.13 ± 0.17, 1.68 ± 0.1, and 5.23 ± 0.04 g L-1 of lactate, succinate, and acetate, respectively. Moreover, the strain C. myxofaciens BPM1 was capable of synthesizing a small amount of ethanol, with a resulting concentration ranging from 0.67 ± 0.05 to 1.46 ± 0.03 g L-1. This work shows that the strain C. myxofaciens BPM1 is a potential source of interesting bio-based chemicals for a wide range of industrial applications. In addition, the inexpensive fermentation process using A. donax hydrolysate and corn steep liquor as carbon and nitrogen sources could be suitable for economical and efficient production of succinic acid in industrial processes.