After attending the local St. Catherine's Academy in Belize City (the basis for St. Cecilia's Academy in Beka Lamb), Edgell studied journalism at the school of modern languages at the Polytechnic of Central London and continued her education at the University of the West Indies. She worked as a journalist serving as the founding editor The Reporter. She has also lived for extended periods in such diverse places as Jamaica, Nigeria, Afghanistan, Bangladesh and Somalia, working with development organizations and the Peace Corps. She has been director of women's affairs for the government of Belize, lecturer at the former University College of Belize (forerunner to the University of Belize) and she was an associate professor in the department of English at Kent State University, Kent, Ohio, where she taughtcreative writing and literature. Edgell also tours internationally, giving book readings and delivering papers on the history and literature of Belize. She is considered Belize's principal contemporary writer.

Edgell is married to American educator Al Edgell, who had a decades long career in international development. They have two children, Holly, a journalism professor at the Missouri School of Journalism, and Randall, a physician specializing in stroke treatment and prevention.

Edgell has also contributed extensively to the Belizean Writers Series, published by local publishing house Cubola Productions. She edited and contributed stories to the fifth book in the series, Memories, Dreams and Nightmares: A Short Story Anthology of Belizean women writers, published in 2004.

She was made a Member of the order of the British Empire in the 2007 Queen's Birthday Honour List. In 2009 the University of the West Indies conferred upon her the honorary degree D.Litt at graduation ceremonies in Cave Hill, Barbados.

Her first novel, Beka Lamb, published in 1982, details the early years of the nationalist movement in British Honduras from the eyes of a teenage girl attending high school in the colony; given that it was published a year after Belize became independent this was the first novel to be published in the new nation. Beka Lamb also gained the distinction of being Belize's first novel to reach beyond its borders and gain an international audience, winning Britain's Fawcett Society Book Prize, a prize awarded annually to a work of fiction that contributes to an understanding of women's position in society today. Her subsequent novel, In Times Like These (1991) portrayed the turmoil of nearly independent Belize from the point of view of another female protagonist, this time the adult director of women's affairs (a post Edgell once held). The Festival of San Joaquin (1997), her third novel told the story of a woman accused of murdering her husband, and in her short stories, Edgell skillfully explores the layers of Belize's complicated social and racial stratification through the lens of her female protagonists. Edgell has said she would eventually like to write about male protagonists as well as her extensive travels across the world.

Edgell's fourth novel was published by Heinemann's Caribbean Writers Series in January 2007. The events of Time and the River unfold during the heyday of slavery in Belize. It focuses on the life of a young slave woman, Leah Lawson, who eventually (through marriage) becomes a slaveowner herself. She even finds herself in the position of owning her own family members. The story is told against the backdrop of the brutal forestry slavery of the time and slave revolts, true historical moments in the history of the country that is now known as Belize.

Edgell released this book in Belize at the end of March with appearances at the University of Belize, Belmopan and in Belize City.

Edgell's third novel, "The Festival of San Joaquin," will be re-issued by Macmillan Caribbean in October 2008.