Mycobacterial periprosthetic joint infection (PJI) is very rare and is generally associated with an immunosuppressive environment. Few large-scale studies of this unusual PJI have been conducted. The current study was performed to assess the clinical features and outcomes following two-stage re-implantation for mycobacterial PJI after primary total knee arthroplasty (TKA). We conducted a retrospective review of data collected from our database involving ten cases of two-stage re-implantation manifesting mycobacterial PJI. Patients were followed for at least five years or until recurrent infection. The mean follow-up duration in patients who remained free of infection was 7.5 years (range 5-9.5 years). Seven patients (70%) belonged to the American Society of Anesthesiologists' grade 3 or 4. The surgical protocol entailed resection arthroplasty and cement spacer insertion with vigorous debridement, followed by at least six weeks of systemic antimicrobial therapy and delayed re-implantation in all patients. The median duration from resection arthroplasty to re-implantation was 5.3 months (range 2-10.5 months). Following re-implantation, five patients with Mycobacterium fortuitum were treated with amikacin for six weeks and oral clarithromycin for three months. Five patients infected with M. tuberculosis received anti-tuberculosis medications immediately after pathogen isolation, for a period of 12 months. Mycobacterial PJI can be treated successfully via resection arthroplasty and delayed re-implantation combined with proper antimicrobial agents. Suspicious infection or loosening after primary TKA, particularly in an immunosuppressive environment, warrants the attention of an orthopedic surgeon to consider the possibility of unusual PJI.