That could mean lower prices for shoppers - though consumer experts say it's far from guaranteed.
The antitrust settlement is one of the largest in U.S. history.
If it gets court approval, it should resolve most claims in nationwide litigation going back to 2005.
Merchants have long accused the payment giants of charging inflated fees - up to 3.5% per transaction - when customers swipe a credit or debit card.
Under the new deal, Visa and Mastercard will reduce and cap fees over a specified number of years.
Retailers will also get more discretion to impose surcharges on cards with high fees, discouraging shoppers from using them.
Court papers show the reductions and caps are worth just under $30 billion.
Both firms denied any wrongdoing in agreeing to settle.
Many critics were unimpressed by the outcome, pointing out that the reductions were only temporary.
One industry expert said the U.S. would still have the highest card fees in the developed world even after the agreement.
