FedEx Corp. is offering big discounts to woo online merchants to its air network as it seeks to refashion a delivery system ill-equipped for the rise of e-commerce.

The shipping giant FDX, +1.16% , which is ending an air-shipping contract with Amazon.com Inc. AMZN, +0.66% later this month, is cutting prices for some customers of its Express network, according to people familiar with the matter. That includes offering guaranteed two-day air service for the same price as shipping items through its Ground division, the people said.