Background Critically ill COVID-19 patients are highly susceptible to opportunistic fungal infection due to many factors, including virus-induced immune dysregulation, host-related comorbidities, overuse and misuse of antibiotics or corticosteroids, immune modulator drugs, and the emergencies caused by the pandemic. This study aimed to assess the incidence, identify the potential risk factors, and examine the impact of fungal coinfection on the outcomes of COVID-19 patients admitted to the intensive care unit (ICU). Methods A prospective cohort study including 253 critically ill COVID-19 patients aged 18 years or older admitted to the isolation ICU of Zagazig University Hospitals over a 4-month period from May 2021 to August 2021 was conducted. The detection of a fungal infection was carried out. Results Eighty-three (83) patients (32.8%) were diagnosed with a fungal coinfection. Candida was the most frequently isolated fungus in 61 (24.1%) of 253 critically ill COVID-19 patients, followed by molds, which included Aspergillus 11 (4.3%) and mucormycosis in five patients (1.97%), and six patients (2.4%) diagnosed with other rare fungi. Poor diabetic control, prolonged or high-dose steroids, and multiple comorbidities were all possible risk factors for fungal coinfection [OR (95% CI) = 10.21 (3.43–30.39), 14.1 (5.67–35.10), 14.57 (5.83–33.78), and 4.57 (1.83–14.88), respectively]. Conclusion Fungal coinfection is a common complication of critically ill COVID-19 patients admitted to the ICU. Candidiasis, aspergillosis, and mucormycosis are the most common COVID-19-associated fungal infections and have a great impact on mortality rates.