Early mobilization after surgery is a cornerstone of the Enhanced Recovery After Surgery (ERAS) programs in total hip arthroplasty (THA) or total knee arthroplasty (TKA). Our goal was to determine the time to mobilization after this surgery and the factors associated with early mobilization. This was a predefined substudy of the POWER.2 study, a prospective cohort study conducted in patients undergoing THA and TKA at 131 Spanish hospitals. The primary outcome was the time until mobilization after surgery as well as determining those perioperative factors associated with early mobilization after surgery. A total of 6093 patients were included. The median time to achieve mobilization after the end of the surgery was 24.áhours 16.Çô30. 4,222 (69.3%) patients moved in .ëñ 24.áhours after surgery. Local anesthesia OR.á=.á0.80 (95% confidence interval CI: 0.72.Çô0.90); p.á=.á0.001, surgery performed in a self-declared ERAS center OR = 0.57 (95% CI: 0.55.Çô0.60); p.á<.á0.001, mean adherence to ERAS items OR.á=.á0.93 (95% CI: 0.92.Çô0.93); p.á<.á0.001, and preoperative hemoglobin OR.á=.á0.97 (95% CI: 0.96.Çô0.98); p.á<.á0.001 were associated with shorter time to mobilization. Most THA and TKA patients mobilize in the first postoperative day, early time to mobilization was associated with the compliance with ERAS protocols, preoperative hemoglobin, and local anesthesia, and with the absence of a urinary catheter, surgical drains, epidural analgesia, and postoperative complications. The perioperative elements that are associated with early mobilization are mostly modifiable, so there is room for improvement.