Objectives: There is no consensus on the postoperative 30-day mortality, complication rates, and their risk factors post lower limb amputations (LLA) in the literature, especially in Saudi Arabia. To address this gap, we assessed these three parameters in our patients who underwent LLAs. Methods: We conducted a retrospective cross-sectional study in King Abdulaziz Medical City, Riyadh, Saudi Arabia, between 2015 and 2019. Using non-probability purposive sampling, we targeted 318 adults who underwent LLA at our hospital. The primary outcome variables were postoperative 30-day mortality and complications, such as stump pain, wound infections, hemorrhage, and acute kidney injury. In addition, we collected data on demographics, comorbidities, and clinical course from electronic medical records. Results: We assessed 318 patients (mean age = 65.7 [SD = 0.840] years), most of whom were male patients (68.6%) with endocrine and metabolic disorders (92.1%). Most amputees (87.1%) had peripheral vascular diseases as the main indication for LLA at an above-knee level (62.6%). The 30-day mortality and complication rates were 6.6% and 74%, respectively. Intermediate complications predominated (57%), with stump pain (17.3%) and phantom limb pain (15.4%) being the most common. Thirty-day mortality was significantly associated with some patient characteristics and comorbid kidneys and neurological disorders. The immediate, intermediate, and late complications were significantly related to smoking and several renal, vascular, and respiratory disorders. Conclusion: Calculating the 30-day mortality and complication rates after LLA and mapping the associated risk factors helped identify high-risk patients, deliver better treatment, lower medical costs, and establish protective measures.