The Derry-based Professor has been acting in the role on an interim basis for over a year.
This week Health Minister Robin Swann made the appointment permanent following an external recruitment process.
He said: “The mental health and wellbeing of our population is a priority which has been further highlighted during the COVID-19 pandemic. Appointing a Mental Health Champion is another key step to ensuring those suffering from mental ill health will have access to the services they need, when they need them.
"I am delighted that Professor O’Neill has agreed to continue her crucial work that she started as Interim Mental Health Champion.”
During her time as Interim Mental Health Champion, Professor O’Neill has been an advocate for mental health at both public and governmental levels.
She led a mental health and wellness campaign throughout the winter pandemic restrictions and has been an advisor to the Department of Health and Executive colleagues on the mental health impact of the COVID-19 pandemic.
Professor O’Neill said: “I am delighted to continue as the Mental Health Champion for Northern Ireland, so that the voices of those who struggle with their mental health are heard, and that their voices influence policy and practice to ensure that good mental health and wellbeing is a priority across Government Departments.
“The 10-year Mental Health Strategy is a positive step in improving mental health services and demonstrates why mental health must be a key priority for Northern Ireland. I look forward to continuing my work with Minister Swann, the Executive, those with lived experience of mental ill health and those who provide services on the ground, to ensure that the actions laid out in the strategy are delivered to help Northern Ireland to flourish as we recover from the current pandemic and into the future.”