Prior to working at Bon Appétit, Knowlton worked for Lingua Franca magazine, as well as in the restaurant industry.
He is currently in charge of Bon Appétit's blog presence and the editor of the restaurant section of the magazine. He writes the monthly Restaurant Reporter column, as well as contributing to Starters, the magazine's opening section, writing about overlaps between food and pop culture. He also writes for the magazine about wine, spirits, and cocktails. He is the editor of the Bon Appétit blog, and co-hosts the weekly Bon Appetit podcast. After appearing as a judge on Iron Chef America, in the fall of 2007, he appeared on the Food Network's The Next Iron Chef, acting as a judge for the entire series.
During the course of The Next Iron Chef, many people perceived Knowlton as being too hard on Chef Aarón Sanchez. Anthony Bourdain said that "Knowlton seems not to have disclosed a prior schoolyard incident with a young Aaron "El Guapo" Sanchez—in which Sanchez (it would appear) bullied him mercilessly. He seemed unnaturally eager to send him packing." Michael Ruhlman referred to Knowlton as "cranky," and said Knowlton "is every bit the menace he appears. And it was hard to get to know him off camera—he had a lot of handlers, so it was difficult to get any time with him." Ruhlman intended the comments as a joke, but people responding on his website and others let go on Knowlton with abandon.
- Iron Chef America (occasional judge)
- The Next Iron Chef (judge)
- Gordon Ramsay's Hell's Kitchen (occasional judge)