<p>This study aimed to investigate the effect of peloidotherapy applied in chronic low back pain on pain and central sensitization and its reflections on patients’ sleep quality, fatigue levels, functional capacity, and disability status. In this prospective, randomized, single-blind study, 74 patients were assigned to the Electrotherapy Group (EG: hot pack+TENS+exercise) or Peloidotherapy Group (PG: peloidotherapy+TENS+exercise) for 15 sessions. Treatments were administered 5 days per week for 3 weeks. Clinical assessments were performed pre/post-treatment using the Visual Analog Scale (VAS), Central Sensitization Inventory (CSI), Quebec Back Pain Disability Scale (QBPDS), Functional Assessment of Chronic Illness Therapy–Fatigue (FACIT-F), Pittsburgh Sleep Quality Index (PSQI), and EQ-5D-3&#xa0;L. Both groups showed significant within-group improvements in most outcomes (all <i>p</i> &lt; 0.001), except for the EQ-5D index in the EG. According to the ANCOVA results adjusted for baseline values and pain duration, the PG demonstrated significantly superior post-treatment outcomes compared to the EG in VAS (<i>p</i> = 0.006), EQ-5D index (<i>p</i> = 0.004), and PSQI (<i>p</i> = 0.044) scores. Furthermore, the adjusted delta score analysis confirmed that the improvements in the PG were significantly greater than those in the EG for VAS (<i>p</i> = 0.026), EQ-5D (<i>p</i> = 0.004), and PSQI (<i>p</i> = 0.044). In contrast, no significant between-group differences were observed for CSI, QBPDS, FACIT, or EQ-5D VAS scores (<i>p</i> &gt; 0.05). Both treatments improved pain and central sensitization-related measures, likely due to shared thermal effects. While peloidotherapy showed superior improvements in pain intensity, sleep quality, and health status, no specific superior effect on CSI scores was demonstrated compared to electrotherapy.</p>