Joy grew up in the Montreal area. From an early age, she was sure she would be a veterinarian. But after she received Christ as Saviour at age 19, she discovered that God had other plans! For several years, she worked as a registered nurse. In 1989, she felt a call to China, where she served as an English teacher until 1991.

After returning to Canada, she became senior pastor of Kahnawake Pentecostal Church in a First Nations community near Montreal. During her fifteen years of ministry there, she was also involved in short-term missions to northern First Nations communities and to several African nations. In additiona to her pastoral and missions work, she served as a part-time chaplain in public elementary schools.

In 2007, Joy founded Joy Johnston Ministries Inc. and launched into full-time ministry as a missionary-evangelist. While she ministers in various regions of North America and the world, her main ministry focuses are in Quebec, Canada and Uganda, East Africa. Joy is an itinerant minister with the District of Quebec of the Pentecostal Assemblies of Canada, and a Global Worker under appointment with the PAOC International Missions Department as a Canadian-based "Minister in Partnership." Her life and ministry have been enriched as she moves back and forth between North American and International assignments. Joy's heartbeat is to see people restored to a right relationship with God and ignited with a passion to fulfill the Great Commission. Her preaching style has been characterized as “simple yet powerful,” “communicating life and not only knowledge,” and “demanding a response.”

Joy currently lives in Chateauguay, Quebec. She has a Bachelor's degree in Biblical Studies, and a Master of Divinity degree in Missions. She is an ordained minister with the Pentecostal Assemblies of Canada.