This study aims to systematically describe the demographic profile, treatment characteristics, disease spectrum, illness severity, comorbidity burden, and clinical outcomes of emergency department (ED) in super-elderly patients and to identify independent factors influencing ED length of stay (LOS). A single-center retrospective cross-sectional study was conducted, enrolling 1313 patients aged ≥ 80 years who presented to the ED of a tertiary hospital in Guangzhou between January 2023 and December 2024. Data on demographics, triage levels, diagnoses, comorbidities, outcomes, and LOS were extracted from electronic medical records. Multiple linear regression analysis was used to identify independent predictors of ED LOS. The mean age of patients was (86.0 ± 4.5) years, with a male-to-female ratio of 1:1.07. The majority (78.8%) were triaged as Level II (acute and severe). Common diagnoses included dyspnea (12.8%), fever (11.7%), and chest pain (5.0%). The mean number of comorbidities was 3.8 ± 1.96, and the mean Charlson Comorbidity Index (CCI) score was 5.6 ± 1.63. Patients aged ≥ 90 years had a significantly higher rate of palliative care utilization than those aged 80–89 years (18.5% vs. 7.4%; P < 0.01). Multiple linear regression identified month of presentation (β = –14.087, P = 0.01), season of presentation (β = –39.800, P = 0.02), and number of comorbidities (β = 87.876, P < 0.001) as independent predictors of ED LOS. The model explained 21.4% of LOS variability (adjusted R² = 0.214). Super-elderly ED patients commonly present with nonspecific symptoms and substantial multimorbidity. Disease patterns and outcomes vary significantly by age and gender, while the longevity group (age ≥ 90 years) has a significantly higher palliative care utilization rate. ED LOS is substantially influenced by time factors and the burden of comorbidities. To enhance care efficiency, it is recommended that dynamic resource allocation strategies be adopted and comprehensive geriatric assessments be implemented.