The board voted 5-0 Wednesday during a special meeting following a report by State Department of Education officials.
The grades show 354 schools received an A grade, 499 got a B, 472 received a C, 263 got a D, and 163 received an F.
The A-F letter grade system was pushed by Republicans and signed into law by Gov. Mary Fallin in 2011, but the formula used to determine the grades has drawn fierce criticism from superintendents.
The formula was changed by the Legislature last year to place more of an emphasis on the test scores of students, but reduce the impact of overall school improvement.