Mr Ford, who appointed Ms McAllister to the role when Justice Minister, said she had delivered a successful reform programme to the Prison Service, the benefits of which would continue to be seen.
“I want to thank Sue for her fantastic service in what is an incredibly demanding role,” he said.
“The reforms Sue put in place will have a long-running impact on the service – indeed, much of the staff development she put in place will ensure key positions are filled by local people well into the future.
“While every prison service has its problems, the Northern Ireland Prison Service is in a much better position than when she started and that is a tribute to her. I wish her every success in future.”