The first case of mpox was detected in the United States in a Laboratory Response Network (LRN) laboratory at the Massachusetts Department of Public Health on May 17, 2022. Through previous years of smallpox preparedness efforts by the United States government, testing capacity in LRN laboratories across the United States utilizing the FDA-cleared Centers for Disease Control and Prevention (CDC) Non-variola orthopoxvirus (NVO) test was approximately 6000 tests weekly across the nation prior to the mpox outbreak. By early June 2022, the LRN laboratories had capacity to perform up to 8000 tests per week. As the outbreak expanded, cases were identified in every United States state, peaking at~3000 cases per week nationally in August 2022. Although NVO testing capacity in LRN laboratories exceeded national mpox testing demand overall, LRN testing access in some areas was challenged and test expansion was necessary. CDC engaged with partners and select commercial laboratories early to increase diagnostic testing access by allowing these commercial laboratories to utilize the NVO test. The expansion of testing to commercial laboratories increased testing availability, capacity, and volume nationwide. This was the first time that CDC shared an FDA 510k-cleared molecular test with commercial laboratories to support a public health emergency. Extensive efforts were made to ensure the CDC NVO test was used appropriately in the private sector and that the transfer process met regulatory requirements. These novel methods to expand NVO testing to commercial laboratories increased national testing capacity to 80000 mpox tests/week. Test volumes among these laboratories never exceeded this expanded capacity. The rapid increase in the nation's testing capacity, in conjunction and coordination with other public and private health efforts, helped to detect cases rapidly. These actions demonstrated the importance of highly functional and efficient public health and private sector partnerships for responding to public health emergencies.