When Atkins was aged 12 his family moved to Dayton, Ohio, where his father owned restaurants. Atkins graduated from the University of Michigan in 1951 and received a medical degree from Weill Cornell Medical College in 1955. He had internal medicine and cardiology residencies at hospitals affiliated with the University of Rochester and Columbia University, then specialized in cardiology and complementary medicine, opening an office in the Upper East Side in New York in 1959. He married his wife Veronica when he was 56.

In April 2002, Atkins suffered a cardiac arrest. Atkins stated that his cardiac arrest was due to a chronic infection., and Dr. Patrick Fratellone, Atkins' personal physician and cardiologist, concurred, saying "We have been treating this condition, cardiomyopathy, for almost two years. Clearly, his own nutritional protocols have left him, at the age of 71, with an extraordinarily healthy cardiovascular system." According to CNN reports at the time, Dr. Clyde Yancy, a cardiologist at the University of Texas Southwestern Medical Center in Dallas and a member of the American Heart Association's national board of directors, said: "Despite the obvious irony, I believe there is a total disconnect between the cardiac arrest and the health approach he (Atkins) popularizes."

On April 8, 2003, at age 72, a day after a major snowstorm in New York, Atkins slipped on ice while walking to work, hitting his head and causing bleeding around his brain. He lost consciousness and went into a coma on the way to the hospital. He spent nine days in intensive care, before dying on April 17, 2003.

In 1963, when Atkins weighed 100 kg (224 pounds) due to a diet of junk food, he read a study of a low-starch diet in JAMA based on the work of Alfred W. Pennington and successfully lost weight by following it, which was repeated with 65 of his overweight patients. He appeared on the Tonight show in 1965, and his diet became known as the 'Vogue diet' after a 1970 Vogue article on it. He published Dr. Atkins' Diet Revolution in 1972, which soon sold millions of copies.

He founded the Atkins Center for Complementary Medicine in Manhattan, which had 87 employees in the 1990s, and where he said he treated over 50,000 patients, and founded Atkins Nutritionals in 1998 to promote his low-carbohydrate diet, with revenue of $100 million. He published Dr. Atkins' New Diet Revolution in 1992, which again became a best-seller.

Atkins suggested that "carbohydrate is the bad guy" through extensive research, that it causes the body to overproduce the hormone insulin, a condition called hyperinsulinism, which metabolizes blood glucose and thus makes people feel hungry. He believed that diabetes and obesity are closely linked, calling them "di-obesity", the title of a book he was working on when he died.