Gloria Whelan was born in Detroit, Michigan, on November 23, 1923, to William and Hildegarde (Kilwinski) Rewoldt. She took an interest in reading early in life when books provided solace during a bedridden year with rheumatic fever. She sometimes dictated stories to her baby sitter who would in turn type them up for her. Whelan began writing poetry in elementary school and edited her high school's newspaper.

She earned B.S. and M.S.W. degrees from the University of Michigan in 1945 and 1948, respectively. She married Joseph L. Whelan, a neurologist, in 1948. Over the next thirty years, Gloria Whelan worked as a social worker in Minneapolis and Detroit and raised two children.

In 1972, weary of the hectic pace of life in Detroit, the Whelans moved to a cabin on Oxbow Lake in the woods of northern Michigan, outside the small town of Mancelona. Their peace was soon disturbed, however, by an oil company that intended to drill on their property. Since the Whelans did not own the mineral rights to the land, the company razed three acres and sank an unsuccessful well, after which it departed. The experience inspired Whelan to write a children's novel about a young boy who worked on an oilrig. It was published as A Clearing in the Forest in 1978.

In the quarter century since she was first published, Gloria Whelan has written thirty-one works of historical and contemporary fiction for children and young adults. Although many of her books are set in the rural environs of northern Michigan (leading many that critics to consider her only a regional author), Whelan has also produced works set in exotic locales such as China, Vietnam, India, communist Russia, and Kenya. Whelan won the National Book Award for Young People's Literature in 2000 for Homeless Bird, the story of a young widow in India abandoned by her mother-in-law.