Meredith Costain grew up in West Gippsland, Victoria. She writes fiction, non-fiction and poetry, and has edited children's literature magazines. Her first poem, titled My Little Creek, was published in The Age newspaper c1964. After attending university, Meredith became a teacher.
Meredith's first novel was publisher under the writing name Gemma Carey. Musical Harriet was the first work of children's fiction penned under her own name. Meredith's work has been shortlisted for children's choice awards YABBA and WAYBRA, as well as the CBCA Book of the Year Awards, and The Environment Award for Children's Literature.
In 2018, Meredith was awarded the Graham Davey Citation for her services to Australian children's literature.