An elderly man who has a farm near Alton Brown's home, he prides himself on his home-grown produce and enters them regularly in county fair food contests. Brown used to pilfer from McGregor's prized tomato patch, but soon stopped when McGregor realized the tomato dishes Brown gave him were made with his own tomatoes. McGregor also has the skills to produce larger-than-average produce, making a potato that weighed 29 lb (13 kg), although it lost in the "Big Food" contest to Brown's modest olive. McGregor also appears in the eggplant episode and brings Brown too many eggplants to use, often using wheelbarrows and cardboard boxes as delivery methods.

The character is named after the same character in the Peter Rabbit series of books by Beatrix Potter.

Farmer McGregor is portrayed by Bill Greeley.