Helen Markley Miller was born in Cedar Falls, Iowa. In 1919 she graduated from the Iowa Teachers College in her city of birth. Subsequently she worked as an English teacher until her marriage. After her husband died, she picked up teaching again.

In 1953 Doubleday published Miller's first book, Promenade All. In 1954 she graduated with a master's degree from Western State College of Colorado. Her master thesis, Let me be a free man, was about Chief Joseph. Like many of her books, it was a fictionalized biography.

After her graduate studies, Miller lived in McCall, Idaho and wrote 21 more books. All were published by major publishing houses. She was represented by literary agent Barthold Fles. Miller had taught at the University of Idaho. In 1969 she headed the Governor's Conference on Idaho Libraries.

Helen Markley Miller's only son, Andrew Markley "Mack" Miller, participated as a cross-country skier in the Winter Olympics of 1956 and 1960. Mack Miller works as a ski trainer and continues to live in Mccall. Mack and his sport formed the inspiration to Mrs. Miller's sixth novel, Ski fast, ski long.

At least one of her books has been translated to German.