A high risk of thrombotic complications has been observed among severely ill COVID-19 patients. Viscoelastic tests (VET) have shown a hypercoagulable profile in these patients, although so far there is no clear evidence on the use of these tools as predictors of risk in the clinical course of patients. In this study we aimed to evaluate the association between Quantra® sonorheometry VET parameters, standard coagulation tests and inflammatory markers in 69 patients with COVID-19 on hospital admission with disease severity and outcome. Inflammatory markers were elevated in a high percentage of patients, as were coagulation-related parameters such as fibrinogen and D-dimer levels. Quantra® sonorheometry analysis revealed increased clot stiffness (CS), especially due to increased fibrinogen contribution (FCS) in 63.7%. Analysis of clot stability to lysis (CSL) on the Quantra showed a value of 100%, suggesting hypofibrinolysis, in 32.4%. Age > 65 years, elevated values of fibrinogen, D-dimer, LDH, increased CS and CSL were significantly associated with worsening disease. The combination of elevated FCS and D-dimer values showed a particularly high prognostic value in distinguishing patients with severe symptomatology. In conclusion, FCS measured by Quantra® system and its combination with D-dimer could be established as a powerful tool to identify poor prognosis in COVID-19 patients on hospital admission.