Background Globally, critical illness results in millions of deaths every year . Although many of these deaths are potentially preventable, the basic, life-saving care of critically ill patients can be overlooked in health systems . Essential and Emergency Care (EECC) has been devised as the care that should be provided to all critically ill patients in all hospitals in the world . EECC includes the effective care of low-cost and low-complexity for the identification and timely treatment of critically ill patients across all medical specialities . This study aimed to specify the content of EECC and additionally, given the surge of critical illness in the ongoing pandemic, the essential diagnosis-specific care for critically ill patients with COVID-19 . Methods A Delphi process was conducted to seek consensus (> 90% agreement) among a diverse panel of global clinical experts . The panel was asked to iteratively rate proposed treatments and actions based on previous guidelines and the WHO Basic Emergency Care . The output from the Delphi was adapted iteratively with specialist reviewers into a coherent, user-friendly, and feasible EECC package of clinical processes plus a list of hospital resource requirements . Results The 272 experts in the Delphi panel had clinical experience in different acute medical specialties from 59 countries and from all resource settings . The agreed EECC package contains 40 clinical processes and 67 hospital readiness requirements . The essential diagnosis-specific care of critically ill COVID-19 patients has an additional 7 clinical processes and 9 hospital readiness requirements . Conclusion The study has specified the content of the essential emergency and critical care that should be provided to all critically ill patients. Implementation of EECC could be an effective strategy to reduce preventable deaths worldwide . As critically ill patients have high mortality rates in all hospital settings, especially where trained staff or resources are limited, even small improvements would have a large impact on survival . EECC has a vital role in the effective scale-up of oxygen and other care for critically ill patients in the COVID-19 pandemic . Policy makers should prioritise EECC, increase its coverage in hospitals, and include EECC as a component of universal health coverage.