Transferring critically ill patients between intensive care units is often required in the UK, particularly during the COVID-19 pandemic. However, there is a paucity of data examining clinical outcomes following transfer of patients with COVID-19 and whether this strategy affects their acute physiology or outcome. We investigated all transfers critically ill patients with COVID-19 between three different hospital intensive care units, between March 2020 and March 2021. We focused on inter-hospital intensive care unit transfers, i.e. those patients transferred between intensive care units from different hospitals and compared this cohort with intra-hospital intensive care unit transfers, i.e. patients moved between different intensive care units within the same hospital. A total of 507 transfers were assessed, of which 137 met the inclusion criteria. Forty-five patients underwent inter-hospital transfers compared with 92 intra-hospital transfers. There was no significant change in median compliance 6 hours pre-transfer, immediately post-transfer and 24 hours post-transfer in patients who underwent either intra-hospital or inter-hospital transfers. For inter-hospital transfers, there was an initial drop in median PaO2/FiO2 ratio: from median (IQR [range]) 25.1 (17.8–33.7 [12.1–78.0]) kPa 6 hours pre-transfer to 19.5 (14.6–28.9 [9.8–52.0]) kPa immediately post-transfer (p<0.05). However, this had resolved at 24 hours post-transfer: 25.4 (16.2–32.9 [9.4–51.9]) kPa. For intra-hospital transfers, there was no significant change in PaO2/FiO2 ratio. We also found no meaningful difference in pH; PaCO2;, base excess; bicarbonate; or norepinephrine requirements. Our data demonstrate that patients with COVID-19 undergoing mechanical ventilation of the lungs may have short-term physiological deterioration when transferred between nearby hospitals but this resolves within 24 hours. This finding is relevant to the UK critical care strategy in the face of unprecedented demand during the COVID-19 pandemic.