Pruess graduated from the University of California, Berkeley, received a master's degree in English from Stanford University, and a certificate of graduate studies in French literature and arts from the Sorbonne. She was the director of the Cookingstudio, a school that she founded that held classes in a number of New Jersey branches of the Kings Supermarket chain, from 1982 to 1987. Her parents are Harriet Rubens of Los Angeles and the late Gerald Rubens.

She became a widow before marrying Bob Lape, a restaurant critic at Crain's New York Business and host of "Bob Lape's Dining Diary" (a review broadcast on WCBS-AM in Manhattan), in 2004. Mr. Lape knew about Ms. Pruess's supermarket cooking schools and reviewed her first cookbook in 1988, before meeting Pruess. They met again in January 2003, at the memorial service for Lape's wife and again months later when a female friend of Lape's suggested that he come along on a double date. "He was skeptical when the friend suggested that the woman in question was 'very funny'", but when name was Joanna Pruess was mentioned Mr. Lape said, "Great!" adding: "I thought she was a fascinating woman. I had wanted to see her, but had not gotten around to it. The invitation galvanized me."

The couple resides in the Kingsbridge section of the Bronx, in New York City.

On the subject of bacon, Pruess contends that its popularity (bacon mania) is linked to the Atkins diet and South Beach diet regimens, which "gave dieters permission to indulge in fatty foods". "People are craving comfort, people are craving flavor, they're craving style," Pruess said. She's also noted that, "You need so little of it to add so much flavor." She suggests substituting bacon drippings for the oil or butter in the basic directions for popping corn. "Bacon is far more than a food. It is a happy state of mind. It excites people to the point where some aficionados liken it to illicit pleasures," she wrote.