"We're no longer a morning day part business. We're a business throughout the day," he told CNBC's "Squawk on the Street."
While most restaurant-and-retail companies in its class are struggling to put up 5 percent growth at U.S. stores, Starbucks on Thursday reported comparable-store sales in the Americas increased 9 percent in its most recent quarter. That beat estimates of 7.2 percent, according to StreetAccount.
Starbucks has offered its breakfast customers coupons to entice them to come back later in the day, and a promotion offers bonuses to Starbucks Rewards members when they load cash onto their loyalty card.
Rolling out mobile pay infrastructure also has significantly contributed to sales, Schultz said. The chain served 18 million more Americans in the final quarter of 2015 than it did during the same period last year, he added.
"At a time in America where every bricks-and-mortar retailer is struggling just to be even or parity in traffic, not only are we driving comp-store sales at 8 percent globally and 9 percent in the U.S., but we are driving 4 percent incremental traffic. It's unheard of at our scale," he said.