In its prime, Chipotle Mexican Grill positioned itself as the paragon of cool casual dining, a darling of Wall Street, a restaurant industry innovator.

Basically, nothing like Taco Bell.

How the tables have turned. Chipotle has spent the past few years struggling to recover from a string of food safety crises, abandonment by its customers and a plunging stock price. For help, the chain is turning to the quick-serve cousin that many once thought was inferior.

Brian Niccol, the chief executive of Taco Bell, will replace Chipotle’s founder, Steve Ells, as chief executive on March 5, Chipotle said on Tuesday. Mr. Niccol is tasked with replicating his success transforming Taco Bell from a fast food afterthought to a social media-savvy company with sleek new stores and the hugely popular Doritos Locos Tacos.

“His expertise in digital technologies, restaurant operations and branding make him a perfect fit for Chipotle as we seek to enhance our customer experience, drive sales growth and make our brand more relevant,” Mr. Ells said in a statement.