Cargill has begun an external and internal search for Ms. Miller’s successor, according to a spokeswoman. The company declined to make Ms. Miller available for an interview, or to say where she is going. 

Ms. Miller’s departure follows the Jan. 1 promotion of Brian Sikes, Cargill’s former chief operating officer, to the role of chief executive officer. Mr. Sikes succeeded

David MacLennan,

who took over as executive chair of the company’s board after nine years as CEO.

Joanne Knight,

vice president of finance in Cargill’s agriculture supply-chain division—which includes its ocean transportation and world trading businesses—will serve as acting CFO, the company said. Before joining Cargill in July 2019, Ms. Knight worked for a decade at

General Mills Inc.,

the packaged-food company. 

Cargill, one of the world’s biggest food suppliers, buys crops from farmers, trades commodities and processes meat. As a private company, it doesn’t face the same financial disclosure requirements as publicly traded firms. In 2020, it ended its longstanding practice of providing quarterly results, and instead reports numbers for its fiscal year in its annual report.

In August, Cargill said it had $165 billion in revenues in the financial year ended May 31, a 23% increase over the year earlier. Over the past year, the company and its competitors have benefited from high commodity prices and ongoing supply constraints, driven in part by Russia’s war in Ukraine.

A key challenge for Ms. Miller’s successor will be just getting to know Cargill, a global corporation that makes products ranging from animal feed to chocolate, said John Rogers, a senior vice president at

Moody’s Corp.

, the credit ratings firm. “That’s the biggest thing—getting a good understanding,” he said.

During Ms. Miller’s tenure at Cargill, the company, alongside investment firm Continental Grain Co., completed a $4.5 billion acquisition of Sanderson Farms Inc., one of the country’s largest poultry producers. Under the transaction, Cargill and Continental combined Sanderson with Wayne Farms LLC, a poultry company owned by Continental. Cargill and Continental evenly share ownership of the combined company, now known as Wayne-Sanderson Farms.

“Over the last few years, we have further strengthened our business model, expanded our business portfolio and are well-positioned for long-term success,” Mr. Sikes, Cargill’s new CEO, said in a press release announcing Ms. Miller’s departure. 

—Colin Kellaher contributed to this article.

Write to Kristin Broughton at Kristin.Broughton@wsj.com