Quality, timely diagnosis is an essential enabler of health for all, yet diagnosis remains the weakest link in the care cascade. The COVID-19 pandemic has further highlighted how access to timely, accurate diagnostics is fundamental to effective healthcare and ensuring global health security. Progress has been made during the pandemic to enhance testing and surveillance capacity, but access to testing is still highly inequitable in low- and middle-income countries. As a result, meaningful action is needed to leverage the progress made during the COVID-19 pandemic in diagnostics and close the gaps that remain. FIND, the global alliance for diagnostics, alongside the Coalition for Epidemic Preparedness Innovations, is coordinating the ambitious mission to create the tests necessary to respond to the next global threat within 100 days, as part of the 100 Days Mission. The support of the G7 will be vital in achieving these goals. This policy brief outlines our policy recommendations for the G7 to achieve the 100 Days Mission and create a future with equitable access to diagnostics and strong global health security.