Data on outcomes of patients receiving mechanical ventilation (MV) in China are scarce.To investigate factors associated with the prognosis of patients given MV in the intensive care unit (ICU).A 12-year (January 1, 2006–December 31, 2017) retrospective cohort study.ICU of Beijing Geriatric Hospital, China.A total of 905 patients aged ≥16 years given MV during the study period.None.Among 905 patients included (610 men; median age, 78 years; Acute Physiology and Chronic Health Evaluation [APACHE]-II score, 27.3 ± 8.9), 585 survived (388 men; median age, 77 years; average APACHE-II score, 25.6 ± 8.4), and 320 died in the ICU (222 men; median age, 78 years; APACHE-II score, 30.6 ± 8.9). All-cause ICU mortality was 35.4%. In patients aged <65 years, factors associated with ICU mortality were APACHE-II score (odds ratio [OR], 1.108; 95% confidence interval [95% CI], 1.021–1.202; P = .014), nosocomial infection (OR, 6.618; 95% CI, 1.065–41.113; P = .043), acute kidney injury (OR, 17.302; 95% CI, 2.728–109.735; P = .002), invasive hemodynamic monitoring (OR, 10.051; 95% CI, 1.362–74.191; P = .024), MV for cardiopulmonary resuscitation (OR, 0.122; 95% CI, 0.016–0.924; P = .042), duration of MV (OR, 0.993; 95% CI, 0.988–0.998; P = .008), successful weaning from MV (OR, 0.012; 95% CI, 0.002–0.066; P < .001), and renal replacement therapy (OR, 0.039; 95% CI, 0.005–0.324; P = .003). In patients aged ≥65 years, factors associated with mortality were APACHE-II score (OR, 1.062; 95% CI, 1.030–1.096; P < .001), nosocomial infection (OR, 2.427; 95% CI, 1.359–4.334; P = .003), septic shock (OR, 2.017; 95% CI, 1.153–3.529; P = .014), blood transfusion (OR, 1.939; 95% CI, 1.174–3.202; P = .010), duration of MV (OR, 0.999; 95% CI, 0.999–1.000; P = .043), and successful weaning from MV (OR, 0.027; 95% CI, 0.015–0.047; P < .001).APACHE-II score, successful weaning, and nosocomial infection in the ICU are independently associated with the prognosis of patients given MV in the ICU.