Objectives: Patients with dementia have an increased 30-day mortality after hip fracture. We investigated clinical management including time to surgery, out-of-hours admission and surgery, surgery on weekends, surgery volume per ward, and anesthesia technique for this excess mortality risk. Method: This register- and population-based study comprised 12,309 older adults (age 70+) admitted to hospital for a first-time hip fracture in 2013–2014, of whom 11,318 underwent hip fracture surgery. Cox proportional hazards regression models were applied for the analysis. Results: The overall postoperative 30-day mortality was 11.4%. Patients with dementia had a 1.5 times increased mortality risk than those without (HR = 1.50 [95% CI 1.31–1.72]). We observed no time-to-surgery difference by patient dementia status; additionally, the excess mortality risk in patients with dementia could not be explained by the clinical management factors we examined. Conclusions: Increased mortality in patients with dementia could not be explained by the measured preoperative clinical management. Suboptimal handling of postoperative complication and rehabilitation are to be investigated for their role in the witnessed increased mortality for patients with dementia.