Stew Leonard Sr., a folkloric retailer who expanded his namesake stores into merchandising meccas replete with petting zoos and mechanical singing farm animals, died on Wednesday at a hospital in Manhattan. He was 93.

The cause was complications of pneumonia, his son Stewart Jr. said.

Mr. Leonard opened his original store in Norwalk, Conn., in 1969 as a destination that promised fresh milk because it was built around a bottling plant. “You’d have to own a cow to get it sooner,” his advertisements proclaimed.

Bryan Miller described it in The New York Times as the “Disneyland of Dairy Stores”; “Ripley’s Believe It or Not” called it the “World’s Largest Dairy Store”; and it earned a place in the Guinness World Records for having the highest dollar sales per square foot of selling space.

In 2015, Business Insider praised Kroger’s customer loyalty program and Wegmans’s walk-in beer locker, but it concluded that anyone who had ever set foot in Stew Leonard’s “knows it is miles above the rest.”

The magazine listed 13 reasons Stew Leonard’s was “truly America’s best grocery store.” The first was its customer service policy: “Rule 1: The customer is always right. Rule 2: If the customer is ever wrong, reread Rule 1.”

More than 50 years after the first store opened, Stew Leonard’s has expanded to encompass seven locations earning $600 million annually, and it remains family-owned and operated with an enormously loyal customer base.

Mr. Leonard became Frank Perdue’s biggest wholesale chicken buyer. He arranged with a distributor friend to bottle Paul Newman’s salad dressing. The stores’ chief criterion for employment was an exuberant smile. To keep prices low, the stores have stocked only about 2,000 items — grocery basics — about 3 percent of what chain stores sell.

In 1986, he was presented with a Presidential Award for Entrepreneurial Excellence from Ronald Reagan.

Mr. Leonard retired around 1990, but remained chairman emeritus of the company’s board. Three years later, he was sentenced to prison after pleading guilty to tax fraud for skimming more than $17 million in sales from the Norwalk store; at the time, it was the nation’s largest computer-driven tax evasion case on record.

Many of his devoted patrons who were interviewed afterward seemed more saddened or disappointed then angry. At his sentencing, Mr. Leonard, leaning on a metal cane after hip surgery, said, sobbing: “I’ve hurt my family. I’ve hurt my children. I’ve hurt my customers.”

In a phone interview on Thursday, Stewart Jr. described the fraud as “more of a small business entrepreneurial mistake.” He said that while his father was serving 44 months of a 52-month sentence in a federal prison in McKean, Pa., he lectured retailers about his mistakes in nearby Bradford. Since then he had mentored young entrepreneurs, warning them against “the trap you can fall into of not putting everything into the cash register,” his son said.

Also in 1993, the Connecticut Department of Consumer Protection accused the Norwalk store of short-weighting customers on items like chicken, walnuts and tomatoes. Mr. Leonard said the weight discrepancies were minuscule and were corrected.

Stewart John Leonard was born on Dec. 1, 1929, in Norwalk to Charles Leonard, a hatter who founded Clover Farms Dairy in the early 1920s, and Anna (Stewart) Leonard, a homemaker.

“My dream ever since I was a little boy was to be a milkman,” he told The Times. He graduated from Norwalk High School, but as he was earning a degree from the Ratcliffe Hicks School of Agriculture at the University of Connecticut in Storrs in 1951, his father died, and he and his brother inherited the business.

In 1967, the state condemned the family dairy for a highway, leaving him shattered.

“Milk was all I knew,” he said.

In “Stew Leonard: My Story” (2009, with Scotty Reiss), he wrote that he had asked customers on his milk route for advice on what to do. They suggested that he open a retail store and, without a middleman, continue to sell his dairy products at the same low prices. He soon bought pasture land in Norwalk from a widow who had been a customer of his father’s; she had agreed to sell only if the younger Mr. Leonard agreed to take care of her sheep and chickens, too.

They became part of the petting zoo, which joined the mechanical cows and ducks and various costumed characters who have welcomed customers as they pass through the store along a single wide snaking aisle flanked by free offerings from tempting sample booths.

As Tom Peters and Nancy Austin wrote in “A Passion for Excellence: The Leadership Difference” (1985), “Don’t tell Stew or his customers that food shopping is a bore!”

The store was originally called Clover Farms Dairy, but after a competitor opened a facsimile 20 miles away, and after Mr. Leonard discovered that his father had never trademarked the name, he branded the store as Stew Leonard’s.

The company now has seven stores, in Connecticut, New York and New Jersey.

It is run by Stewart Jr. along with his siblings, Beth Leonard Hollis and Jill Leonard Tavello. In addition to them, Mr. Leonard is survived by his wife, Marianne (Guthman) Leonard; another son, Tom; 13 grandchildren, five of whom work for the company; and 11 great-grandchildren.

In retailing, Mr. Leonard said, the “wow factor” sells, but minding the store is what keeps the business going and growing.

“You’d have to be able to stay on top of it,” he told The Times in 1983, invoking an earthy aphorism from his dairy days. “I still believe that a farmer’s shadow is the best fertilizer.”