Objectives To compare the effectiveness and safety between autologous platelet‐rich plasma (PRP) and Local Anesthetic (LA)/corticosteroid in intra‐articular injection for the treatment of lumbar facet joint syndrome. Methods Forty‐six eligible patients with lumbar facet joint syndrome were randomized into group A (intra‐articular injection with PRP) and group B (intra‐articular injection with LA/corticosteroid). The following contents were evaluated: pain visual analog scale (VAS) at rest and during flexion, and the Roland‐Morris Disability Questionnaire (RMQ), Oswestry Disability Index (ODI), and modified MacNab criteria for pain relief and applications of post‐treatment drugs. All outcome assessments were performed immediately after and at 1 week, 1, 2, 3, and 6 months after treatment. Results No significant difference between groups was observed at baseline. Compared with pretreatment, both group A and group B demonstrated statistical improvements in the pain VAS score at rest or during flexion, the RMQ, and the ODI (P < 0.01). And there were significant differences between the 2 groups on the above‐mentioned items (P < 0.05). For group B, subjective satisfaction based on the modified MacNab criteria and objective success rate were highest (80% and 85%) after 1 month, but only 50% and 20% after 6 months. However, for group A, they increased over time. In addition, there were no treatment‐related complications in either group during follow‐up. Conclusions Both autologous PRP and LA/corticosteroid for intra‐articular injection are effective, easy, and safe enough in the treatment of lumbar facet joint syndrome. However, autologous PRP is a superior treatment option for longer duration efficacy.