Education Minister Jeremy Rockliff has welcomed the move which he said mirrored the government's commitment to extend all Tasmanian Government high schools to Years 11 and 12 by 2022."

"Importantly, the extensions will result in upgrades to school sites which will stimulate the economy and create much needed jobs for Tasmanians as we recover from the impacts of COVID-19," Mr Rockliff said.

"Extension schools are part of a united and concentrated effort to ensure every Tasmanian student is able to successfully complete Year 12 or an alternative appropriate pathway in training or employment."

Catholic Archbishop Julian Porteous said the move came after three years of research and planning to advance the provision of Years 11 and 12 at Catholic colleges in the greater Hobart area.

He said the decision gave certainty to students and parents for the next 20 years.

"From the commencement of the 2023 school year three existing Catholic colleges - St Aloysius Catholic College, MacKillop Catholic College and St Virgil's College will begin to provide year 11 and 12 Catholic education, " Archbishop Porteous said.

"This development has been a cooperative effort, not only for the three colleges involved, but also has engaged a process of close collaboration with St Mary's College and Guilford Young College. It has been very pleasing to observe the desire of all parties to see that Catholic education works together to advance the Catholic formation of young Tasmanians, particularly in the senior secondary area."

Catholic Education Tasmania Executive Director Dr Gerard Gaskin, said the Greater Hobart Catholic College Extension Project was an exciting time for Catholic education and more broadly, for Tasmanian education.

"The benefits will see improved retention to Catholic education and more broadly, Tasmanian education. We're achieving this by providing students with a broader range of pathways to successfully complete their education," Dr Gaskin said.