According to the suit, the consumer electronic retailer advertised lower prices, and then overcharged customers at some Calif. stores.
The district attorneys of Los Angeles, Riverside and San Diego counties filed the case after weights and measures officials documented over-charges during inspections.
Best Buy was ordered to pay $600,000 in penalties, about $175,000 in costs and $100,000 in restitution.
In addition to the penalties and restitution, the company was ordered to institute a special discount program. For the next five years the California stores must offer customers $3 off the lowest advertised price of an item if they are over-charged at checkout.
The company has apologized for the pricing errors. The number of customers who qualify for restitution was not immediately known.
The Associated Press contributed to this report.