The bill passed the Senate by 34-5 Monday after passing in the House by 88-10.
School districts could require students to stay in school until age 18, and if 55 percent of school districts raise the dropout age to 18, the policy will become mandatory four years after the threshold is met, the Louisville, Ky., Courier-Journal reported Tuesday.
Beshear, a Democrat, and his wife Jane, a former teacher, have advocated raising the dropout age during the past several legislative sessions, the newspaper said.
"Today is a good day, for our schools, for our students and for the future workforce of the Commonwealth (of Kentucky)," Beshear said in a statement.
A state report said over 6,200 Kentucky high school students dropped out of school in 2010.