We report a case of a 64-year-old man with end-stage renal failure who was diagnosed with peritoneal dialysis-associated peritonitis caused by a novel species in the genus of Mycolicibacterium (Mycobacterium). This rapidly growing non-tuberculous mycobacterial species was repeatedly isolated from peritoneal fluid. The patient’s symptoms failed to improve despite empirical intraperitoneal antibiotics of cefazolin and ceftazidime, until the removal of the Tenckhoff catheter and commencement of a four-month course of antimycobacterial treatment. Initially identified as M. litorale using Sanger sequencing and analysis of the 16S rRNA, Whole Genome Sequencing (WGS) and genomic analysis revealed instead a novel isolate most closely related to M. litorale that is yet to be taxonomically defined. More than six months after the cessation of antimicrobials, the patient remains well and has been referred for consideration of renal transplantation. This novel Mycolicibacterium species is likely of low virulence but has potential to cause prosthesis-associated infections.