The law signed Monday limits borrowers to four short-term loans a year and caps annual interest rates at 28 percent. The state Legislature passed the bill last month over the objections of industry leaders.
Payday lenders had charged about $15 for every $100 borrowed on a two-week loan, which worked out to an annual interest rate of 391 percent.
Industry leaders argue that the law will force them to close offices and lay off workers.
Strickland, a Democrat, and Republican lawmakers say the loans have trapped customers in a cycle of debt.