Background Major lumbar spine surgery causes severe pain in the postoperative period. There are few studies regarding the effect of erector spinae plane block (ESPB) effect on lumbar surgery and its effect is still controversial. Therefore, the study aimed to investigate the effect of ultrasound-guided low thoracic ESPB on opioid consumption and postoperative pain score. Material and methods Seventy-eight patients undergoing elective open lumbar spine surgery were randomized into two groups. In ESPB group (n = 35) received ultrasound-guided ESPB and in the control group (n = 35), there was no block. Postoperative opioid consumption as morphine equivalent dose, numerical rating scale, mobilization time, discharge time and side effects, bolus deliveries, rescue analgesia doses were evaluated. Results Total opioid consumption as morphine equivalent was higher in the control group than the ESPB group (p = 0.000). Compare with the control group, the numeric rating scale scores were lower in the ESPB group at the 6th, 12th, and 24th hours (p < 0.05). The patient-controlled analgesia button pressing number in the postoperative 24-h period was lower in the ESPB group (p = 0.000). In the postoperative 24-h period, the need for paracetamol in the ESPB group was lower and the difference between the groups was statistically significant (p = 0.008). Rescue analgesia (diclofenac) doses were higher in the control group (p < 0.05). There was no statistically significant difference in terms of side effects and mobilization times. Conclusion ESPB is adequate for postoperative analgesia in patients undergoing lumbar spine surgery and can reduce opioid consumption compared with standard analgesia.