This multicenter study evaluated the IMMY Aspergillus Galactomannan Lateral Flow Assay (LFA) with automated reader for diagnosis of pulmonary aspergillosis in patients with COVID-19-associated acute respiratory failure (ARF) requiring intensive care unit (ICU) admission between 03/2020 and 04/2021. A total of 196 respiratory samples and 148 serum samples (n = 344) from 238 patients were retrospectively included, with a maximum of one of each sample type per patient. Cases were retrospectively classified for COVID-19-associated pulmonary aspergillosis (CAPA) status following the 2020 consensus criteria, with the exclusion of LFA results as a mycological criterion. At the 1.0 cutoff, sensitivity of LFA for CAPA (proven/probable/possible) was 52%, 80% and 81%, and specificity was 98%, 88% and 67%, for bronchoalveolar lavage fluid (BALF), nondirected bronchoalveolar lavage (NBL), and tracheal aspiration (TA), respectively. At the 0.5 manufacturer's cutoff, sensitivity was 72%, 90% and 100%, and specificity was 79%, 83% and 44%, for BALF, NBL and TA, respectively. When combining all respiratory samples, the receiver operating characteristic (ROC) area under the curve (AUC) was 0.823, versus 0.754, 0.890 and 0.814 for BALF, NBL and TA, respectively. Sensitivity and specificity of serum LFA were 20% and 93%, respectively, at the 0.5 ODI cutoff. Overall, the Aspergillus Galactomannan LFA showed good performances for CAPA diagnosis, when used from respiratory samples at the 1.0 cutoff, while sensitivity from serum was limited, linked to weak invasiveness during CAPA. As some false-positive results can occur, isolated results slightly above the recommended cutoff should lead to further mycological investigations.