General Mills Inc. projected higher inflation ahead as the food giant grapples with growing labor, transport and supply-chain costs.

The maker of Cheerios cereal and Betty Crocker cake mix is facing hundreds of disruptions across its operations, ranging from pricier raw ingredients to a shortage of truck drivers, which executives said will push up prices for supermarket customers over the months ahead.

Higher...

General Mills Inc. projected higher inflation ahead as the food giant grapples with growing labor, transport and supply-chain costs.

The maker of Cheerios cereal and Betty Crocker cake mix is facing hundreds of disruptions across its operations, ranging from pricier raw ingredients to a shortage of truck drivers, which executives said will push up prices for supermarket customers over the months ahead.

Higher costs and logistical problems are squeezing General Mills and other U.S. food companies, prompting them to cut their own costs and swelling consumers’ shopping bills. Big food makers including Campbell Soup Co. and Conagra Brands Inc. are charging more for their products as the food industry faces the steepest inflation in a decade, while shrinking some grocery-store packages and dialing back discounts.

Supply chain challenges are hampering General Mills’ ability to fulfill customer orders, executives said, with higher prices leading the company in recent months to raise prices across nearly all its grocery categories around the world.

“Our prices are going to go up for the remainder of the year as we see inflation going up,” said General Mills Chief Executive Jeff Harmening.

Food companies said they are paying more for ingredients and materials, including cooking oil and steel, as costs rise for freight, fuel and labor too. Earlier this month, Campbell said continuing cost increases likely would prompt it to raise prices further for some of its products. The soup maker said elevated costs for items like the steel used in its cans may prompt a second wave of price increases, though these would likely be less widespread than the previous round.

“I think we’ve got more room,” chief executive Mark Clouse said. “However I do think there still are some boundaries.”

J.M. Smucker Co. in August said it would raise its own prices further to combat cost inflation and supply disruptions it sees continuing for longer than executives had previously anticipated. A frost in Brazil and the summer’s heat wave in the U.S. Pacific Northwest hit harvests of coffee and fruit, Smucker said, pushing up costs for commodities used in ground coffee and fruit spreads. The February storm that closed chemical plants across Texas has kept prices high for packaging, Smucker executives said.

Smucker said it plans to pass the higher costs through to consumers, raising prices on coffee and other products.

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General Mills on Wednesday said it now expects input cost inflation between 7% and 8% in its fiscal 2022, up from its previous estimate of 7%. Supply chain challenges are hampering the company’s ability to fill customer orders, executives said, with service levels in the 80th percentile, versus its goal of the high-90th percentile.

“It’s almost whack-a-mole right now,” said Jon Nudi, head of General Mills’ North America retail business. “It really changes on a daily and weekly basis.”

General Mills has resumed “control tower meetings” that it established during the height of the pandemic to enable the company to make decisions more quickly, executives said. The company is trying to address labor shortages by extending lead times with suppliers, using supplemental labor and offering incentives to boost employee attendance in logistics and manufacturing facilities.

Higher costs weighed on General Mills’ profits. While overall sales increased 4%, the company reported $627 million in net income for the quarter ended Aug. 29, down from $638.9 million in the same period last year, as selling, administrative and other expenses increased. Adjusted earnings were 99 cents a share, ahead of analysts’ predictions.

General Mills said it expects strong demand for groceries to continue as consumers continue to spend more time working at home.

Supply-chain problems could hit consumers’ pantries for the coming holiday seasons. Grocery chains are struggling with supply-chain challenges ahead of Thanksgiving, which is typically their busiest time of the year. Some executives said they are preparing for consumers to host larger gatherings than they did late last year—though it is becoming less clear how people will spend holidays as the Delta variant drives Covid-19 cases higher.

Supermarket executives said they are buying goods earlier to ensure they get as many products as possible from suppliers ahead of the holidays. Still, grocery industry officials warned that consumers may not find every brand, flavor or size of food they want for Thanksgiving and Christmas meals. Consumers may also see higher holiday shopping bills as retailers pass down cost increases in transportation, labor and commodities, they said.

Write to Jesse Newman at jesse.newman@wsj.com and Dave Sebastian at dave.sebastian@wsj.com