Elderly patients are less likely to recover from lumbar spine fusion (LSF) as rapidly compared with younger patients. However, there is still a lack of research on the effect of early ambulation on elderly patients undergoing LSF surgery for lumbar degenerative disorders.To evaluate the safety and benefit of ambulation within 24 hours in elderly patients who underwent LSF.A retrospective study.Consecutive patients (aged 65 and older) who underwent elective transforaminal lumbar interbody fusion surgery for degenerative disorders from January 2019 to October 2022.Outcome measures included postoperative complications, postoperative drainage (ml), laboratory test data, length of hospital stay [LOS], readmission and reoperation within 3 months.Early ambulation patients (ambulation within 24 h after surgery) were propensity-score matched 1:1 to a delayed ambulation patients (ambulation at a minimum of 48 h postoperatively) based on age, intraoperative blood loss, and number of fused segments. The incidence of postoperative adverse events (AEs, including rates of complications, readmission, and prolonged LOS) and the average LOS were used to assess the safety and benefit of early ambulation, respectively. Multivariable regression analysis was performed to assess the association between early ambulation and postoperative AEs. The risk factors for delayed ambulation were also determined using multivariable logistic analyses.A total of 998 patients with LSF surgery were reviewed in this study. After excluding 116 patients for various reasons, 882 patients (<24 hours: N = 350, 24-48 hours: N = 230, and >48 hours: N= 302) were included in the final analysis. After matching, gender, BMI, preoperative comorbidities, laboratory test data and surgery-related variables were comparable between the groups. The incidence of postoperative AEs was significantly lower in the EA group (44444.3% vs. 64.0%, p < .001). The average postoperative LOS of the EA group was 2 days shorter than the DA group (6 .5d vs. 8.5d, p <.001). Patients in the EA group had a significantly lower rate of prolonged LOS compared to the DA group (33535.1% vs. 55.3%, p <.001). There was no significant difference in postoperative drainage volumes between the two groups. Multivariable analysis identified older age (OR 1.07, p <.001), increased intraoperative EBL (OR 1.002, p = 0.001), and higher international normalization ratio (OR 10.57, p = 0.032) as significant independent risk factors for delayed ambulation.Ambulation within 24 hours after lumbar spine fusion surgery is independently associated fewer adverse events and shorter hospital stays in elderly patients. Implementing the goal of ambulation within 24 hours after LSF surgery into enhanced recovery after surgery protocols for elderly patients seems appropriate. Older age, increased intraoperative blood loss and worse coagulation function are associated with delayed ambulation.Copyright © 2023. Published by Elsevier Inc.