Purpose Lumbar microdiscectomy (LM) is the most common spinal procedure performed worldwide. Despite surgical training transitioning towards competency-based training, there are no objective methods of assessing competency in performing LM. The aim of this study was to reach expert consensus to create an objective evaluation tool for assessment of LM. Methodology Essential steps for LM and descriptors for “poor”, “average” and “excellent” performance at each step were developed. 16 surgeon experts were consulted and a Delphi methodology was used to obtain consensus on how suitable the steps and descriptors of performance were for including in the assessment tool. Responses were obtained until consensus was achieved for each of these descriptors. Results Twelve experts from multiple institutions participated in the study. After two rounds of evaluations a Cronbach alpha of 0.99 was achieved, indicating a very high level of consensus. Steps and descriptors of performance that >80% of experts rated as 4 were used to create the final objective evaluation tool. Conclusion Using a Delphi methodology expert consensus was achieved for the first time regarding the steps and descriptors of performance for LM. Subsequently an objective assessment tool for LM surgery was created. This tool can identify strengths and weakness in performance and allow competency based assessment.