Background/Objectives: Extramammary Paget’s disease (EMPD) is a rare cutaneous malignancy arising in areas rich in apocrine glands that poses diagnostic and therapeutic difficulties. Although surgery remains the standard of care, achieving clear margins is challenging and recurrence rates are high. This review explores the contribution of non-invasive imaging for diagnosis and monitoring, and evaluates conservative, non-surgical therapies as alternatives to radical surgery. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), a systematic review was conducted: eligible studies included interventional and observational research, as well as case series and reports, assessing non-invasive diagnostic methods or non-surgical treatments for EMPD. Data extraction and risk-of-bias evaluation were performed independently by multiple reviewers, and a narrative synthesis summarized therapeutic outcomes and diagnostic performance. Results: Of 808 identified records, 82 met the inclusion criteria: 66 focused on non-surgical therapies, 15 on diagnostic techniques, and one on both. Reflectance confocal microscopy (RCM) and photodynamic diagnosis (PDD) showed high concordance with histopathology, aiding both diagnosis and margin delineation. Among therapies, topical imiquimod and photodynamic therapy (PDT) demonstrated encouraging response rates, while radiotherapy, laser ablation, and systemic chemotherapy were less consistently reported. Evidence quality was limited by small cohorts, heterogeneous regimens, and variable follow-up. Conclusions: Non-invasive imaging enhances diagnostic accuracy and surgical planning, while non-surgical treatments—particularly imiquimod and PDT—offer viable alternatives in selected cases. Larger prospective studies are needed to establish standardized protocols and clarify long-term outcomes.