To identify phenotypes of Intensive Care Unit (ICU) onset sepsis and its associated harms of delayed time-to-antibiotics.The Medical Information Mart for Intensive Care IV (MIMIC-IV) database was employed to identify patients with ICU onset sepsis. The primary exposure was time-to-antibiotics, as measured from sepsis recognition to first antibiotic administered. Latent profile analysis (LPA) was used to identify phenotypes of sepsis based on individual organ failure score derived from Sequential Organ Failure Assessment (SOFA). Interactions between phenotypes and time-to-antibiotics on 28-day mortality were explored.6246 patients were enrolled in final analysis. The overall 28-day mortality was 12.7%. Delayed time-to-antibiotics was associated with increased 28-day mortality in patients with ICU onset sepsis (HR 1.12, 95% CI 1.08-1.18). Four phenotypes of sepsis were identified: phenotype 1 was characterized by respiratory dysfunction, phenotype 2 was characterized by cardiovascular dysfunction, phenotype 3 was characterized by multiple organ dysfunction, and phenotype 4 was characterized by neurological dysfunction. The adjusted HR of 28-day mortality was 1.16 (95% CI 1.08-1.25) in phenotype 1, and 1.06 (95% CI 1.00-1.13) in phenotype 2, while no significant interaction was observed.Septic patients with respiratory or cardiovascular dysfunction were associated with harms of delayed time-to-antibiotics.