Emma Smith was born Elspeth Hallsmith in 1923 in Newquay, Cornwall, where until the age of twelve, she lived with her mother and father, an elder brother and sister, and a younger brother. Her first book, Maidens' Trip, was published in 1948 and won the John Llewellyn Rhys Memorial Prize. Her second, The Far Cry, was published the following year and was awarded the James Tait Black Memorial Prize.
In 1951 Emma Smith married Richard Stewart-Jones. After her husband's death in 1957 she went to live with her two young children in Wales, where she proceeded to write and have published four successful children's books, one of which, No Way of Telling, was runner-up for the Carnegie Gold Medal. She also published a number of short stories and, in 1978, her novel The Opportunity of a Lifetime. In 2008 The Great Western Beach, her memoir of her Cornish childhood, was published to widespread critical acclaim.
Since 1980 Emma Smith has lived in the London district of Putney.