"All students will need to provide proof of a negative test result before returning to school," Bowser said via Tweeter.
The measure is one of several that Bowser has introduced as the coronavirus Omicron variant spreads in the US capital just days are scheduled to open for the 2022 school year.
According to data from the US Census Bureau and Johns Hopkins University, Washington, DC has reported the highest rate of coronavirus infection in the United States with an average of 1,192 cases per day over the past week.
US health officials, however, have acknowledged that the Omicron cases are mild and have so far not reported any deaths.