Low-grade periprosthetic joint infections (PJIs) are a challenging subset of infections characterized by subtle clinical symptoms, normal or borderline laboratory findings, and a lack of systemic manifestations. These infections, often caused by low-virulence microorganisms like Cutibacterium acnes and coagulase-negative staphylococci, can lead to joint failure even after seemingly successful surgeries. Traditional diagnostic markers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) may fail to detect these infections, with up to one-third of culture-positive cases showing normal values. Advanced biomarkers, such as interleukin-6 (IL-6) and synovial fluid analysis, as well as molecular diagnostics like next-generation sequencing, offer promise but are not yet widely established. Imaging studies and nuclear medicine can aid in differentiating low-grade infections from aseptic loosening but remain complementary tools. Treatment strategies include debridement, antibiotics, and implant retention (DAIR), one-stage or two-stage revision surgery, and long-term antimicrobial therapy. Two-stage revisions remain the gold standard, but one-stage procedures are increasingly viable for low-grade infections caused by non-resistant pathogens. Success rates for treatment vary widely, depending on factors like infection severity, host immune status, and pathogen virulence. Given the diagnostic and therapeutic complexity, a high index of suspicion is crucial, particularly in patients with persistent joint pain post-replacement. Multidisciplinary collaboration involving orthopedic surgeons and infectious disease specialists is essential for accurate diagnosis and effective management. Further research is needed to validate diagnostic criteria and optimize treatment protocols for these insidious infections.