She was influential as a food editor of McCall's and House Beautiful and was at least partially responsible for helping to discover the unknown Julia Child in 1960.

[14][15][16] By 1960, McCully had become an icon in the food industry, bringing noted chefs together, serving as a mentor, a contact with peers, and hosting regular culinary salons in her Upper East Side apartment.

McCully read the manuscript for Mastering the Art of French Cooking and gave it to Jacques Pépin, for whom she had become a surrogate mother, telling him she thought it had merit.

[21][22] Pépin had only been in the United States a few months, when he met McCully through Craig Claiborne, the noted food editor of the New York Times and she took him under her wing.

Pépin was impressed with Child's manuscript, McCully invited her over to dinner for the two to meet, and a life-long collaboration and partnership emerged.

[5] Perhaps her best known were Cooking with Helen McCully beside You (1970), which was recommended by the Chicago Tribune,[26][27] The Other Half of the Egg (1967), written with Pépin[5] and The American Heritage Cookbook (1967), which she edited with Eleanor Noderer,[28][29] an associate from her days at McCall's.

[5] Pépin said McCully's legacy was that she "knew everybody in the country who had a passionate interest in food, and she made it her life’s mission to bring us all together, to encourage us, to boost our careers, and when occasion demanded, to scold us like the children she never had".