Gray has been with Suncorp for five years and was responsible for initiating one of the biggest IT in-sourcing projects in Australian corporate history.
One year after acquiring GIO's IT operations for $1.4 billion in 2001, Gray integrated the company's systems in a project that was delivered on-budget and on time and cut the combined company's infrastructure costs in half.
At the time, the trend was to outsource IT services but Gray decided to bring GIO's systems in-house because of the lack of a suitable IT vendor in the Brisbane area.
In a statement to the Australian Stock Exchange on Wednesday, Suncorp's chief executive John Mulcahy said Gray's position will be taken over by Hemant Kogekar, who is currently the company's general manager of application services.
Mulcahy said the company was grateful for Gray's contribution and praised her leadership during the in-sourcing project.
"At the time, Suncorp was the only Australian financial institution to have embarked on an in-sourcing project of this scale. The project not only bucked the trend among Australian companies... but it was a key initiative in the group's bid to re-engineer the two insurance businesses.
"Carmel will be sorely missed and we wish her all the best in her retirement," said Mulcahy.