Perioperative blood transfusion has been associated with poor outcomes but the impacts of transfusion after fusion for lumbar stenosis have not been well-described. We assessed this effect in a large cohort of patients from 2012 to 2018 in the National Surgical Quality Improvement Program (NSQIP). We evaluated baseline characteristics including demographics, comorbidities, hematocrit, and operative characteristics. We generated propensity scores using baseline characteristics and patients were matched to approximate randomization. We assessed odds of 30-day outcomes including prolonged length-of-stay (LOS), complications, discharge to facility, readmission, reoperation, and death using logistic regression. We identified 16,329 eligible patients who underwent lumbar fusion for stenosis; 1,926 (11.8%) received a transfusion. Before matching, there were multiple differences in baseline covariates including age, gender, BMI, ASA class, medical comorbidities, hematocrit, coagulation indices, platelets, operative time, fusion technique, number of levels fused, and osteotomy. However, after matching, no significant differences remained. In the matched cohorts, transfusion was associated with increased prolonged LOS (OR 1.66, 95% CI 1.45-1.91, p < 0.001), minor complication (OR 1.60, 95% CI 1.20-2.12, p = 0.001), major complication (OR 1.51, 95% CI 1.16-1.98, p = 0.003), any complication (OR 1.54, 95% CI 1.24-1.92, p < 0.001), discharge to facility (OR 1.70, 95% CI 1.48-1.95, p < 0.001), 30-day readmission (OR 1.56, 95% CI 1.23-1.99, p < 0.001), and 30-day reoperation (OR 1.85, 95% CI 1.35-2.53, p < 0.001). Although transfusion is performed based on perceived clinical need, this study contributes to growing evidence that it is important to balance the risks of perioperative blood transfusion with its benefits.