In late December 2019, an outbreak of a novel coronavirus which caused coronavirus disease 2019 (COVID-19) was initiated. Acute kidney injury (AKI) was associated with higher severity and mortality of COVID-19. We aimed to evaluate the effects of comorbidities and medications in addition to determining the association between AKI, antibiotics against coinfections (AAC) and outcomes of patients. We conducted a retrospective study on adult patients hospitalized with COVID-19 in a tertiary center. Our primary outcomes were the incidence rate of AKI based on comorbidities and medications. The secondary outcome was to determine mortality, intensive care unit (ICU) admission, and prolonged hospitalization by AKI and AAC. Univariable and multivariable logistic regression method was used to explore predictive effects of AKI and AAC on outcomes. Out of 854 included participants, 118 patients developed AKI in whom, 57 used AAC and 61 did not.Hypertension and diabetes were the most common comorbidities in patients developed AKI. AAC, lopinavir/ritonavir, ribavirin, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, and corticosteroids had significant higher rate of administration in patients developed AKI. AAC were associated with higher deaths (odds ratio [OR] = 5.13; 95% confidence interval (CI): 3-8.78) and ICU admission (OR = 5.87; 95%CI: 2.81-12.27), while AKI had higher OR for prolonged hospitalization (3.37; 95%CI: 1.76-6.45). Both AKI and AAC are associated with poor prognosis of COVID-19. Defining strict criteria regarding indications and types of antibiotics would help overcoming concomitant infections and minimizing related adverse events.