Purpose Presumed benefits of erector spinae plane blocks (ESPB) include an enhanced safety profile and few complications. There are few large series, which report the incidence of complications associated with ESPB on a procedure-specific basis. The objective of this retrospective cohort study was to estimate the incidence of complications of ESPB in a large series of patients undergoing lumbar spine surgery. Patients and Methods We included 342 consecutive patients who underwent any primary lumbar spine surgery via posterior approach (November 2018–July 2020). All patients received bilateral ultrasound-guided ESPB. The primary study outcome was the incidence of any perioperative complication, defined a priori as sensory, motor, hematologic, hemodynamic or respiratory complication consistent with plausible contribution from the ESPB. Secondary outcomes included the incidence of numeric rating scale (NRS) pain scores ≥7 in the post anesthesia care unit (PACU) and risk factors associated with NRS ≥7 (age, sex, ASA class, BMI, opioid tolerance, surgical type, and duration). Results We did not identify any pre-specified complications associated with ESPB. There was one unilateral pneumothorax, in one patient, deemed unlikely to have been related to ESPB. NRS ≥7 was found in 17/342 patients (5%) and was independent of any background differences or risk factors assessed. Conclusion Ultrasound guided ESPB for lumbar spine surgery was associated with zero complications, no interference with intraoperative neuromonitoring or the early postoperative neurological examination, and low incidence of poorly controlled pain in the PACU. These results help to establish procedure-specific risks and benefits of ESPB for spine surgery.