OBJECTIVE: To investigate whether early postoperative walking is associated with "best outcome" and no opioid use at 1 year after lumbar spine surgery and establish a threshold for steps/day to inform clinical practice. DESIGN: Secondary analysis from randomized controlled trial. SETTING: Two academic medical centers in the United States. PARTICIPANTS: We enrolled 248 participants undergoing surgery for a degenerative lumbar spine condition (N=248). A total of 212 participants (mean age, 62.8±11.4y, 53.3% female) had valid walking data at baseline. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Disability (Oswestry Disability Index), back and leg pain (Brief Pain Inventory), and opioid use (yes vs no) were assessed at baseline and 1 year after surgery. "Best outcome" was defined as Oswestry Disability Index ≤20, back pain ≤2, and leg pain ≤2. Steps/day (walking) was assessed with an accelerometer worn for at least 3 days and 10 h/d at 6 weeks after spine surgery, which was considered as study baseline. Separate multivariable logistic regression analyses were conducted to determine the association between steps/day at 6 weeks and "best outcome" and no opioid use at 1-year. Receiver operating characteristic curves identified a steps/day threshold for achieving outcomes. RESULTS: Each additional 1000 steps/d at 6 weeks after spine surgery was associated with 41% higher odds of achieving "best outcome" (95% confidence interval [CI], 1.15-1.74) and 38% higher odds of no opioid use (95% CI, 1.09-1.76) at 1 year. Walking ≥3500 steps/d was associated with 3.75 times the odds (95% CI, 1.56-9.02) of achieving "best outcome" and 2.37 times the odds (95% CI, 1.07-5.24) of not using opioids. CONCLUSIONS: Walking early after surgery may optimize patient-reported outcomes after lumbar spine surgery. A 3500 steps/d threshold may serve as an initial recommendation during early postoperative counseling.