Derek Mackay said it was essential to act without delay after the Ferguson Marine (FMEL) shipyard last week that it was poised to go into administration placing 350 jobs at risk.
The Government also remains open to other investors to ensure two ferries being built at the yard are completed.
It comes after Ferguson Marine's sole shareholder Jim McColl was strongly critical of the move towards public ownership at the weekend , saying it made no economic sense.
But Mr Mackay said to the Scottish Government has been working for over two years to find a resolution to the difficulties the yard. The firm has been locked in dispute with Government-owned ferry firm Cal Mac over major overruns on the "fixed cost" £97 million contract.
“Our preference has been to identify viable commercial options to keep the yard going and to finish the vessels. No such solutions have come forward," Mr Mackay said.
“The Scottish Government has now indicated to all relevant parties that we are ready and willing to take Ferguson Marine into public ownership and deliver the ferries to secure the continued employment of the workforce in the yard.
“There remains a process to go through to secure the transfer of the yard to the Scottish Government, and we are hopeful that all parties recognise the importance of completing that transfer as quickly and as smoothly as possible.
“While we are open to engaging with any parties with a serious interest in investing in and securing a future for the shipyard, it is essential the government acts now to secure the completion of the ferries and continuity of employment at Fergusons.”
The government's takeover of the yard follows Mr McColl's rescue of the yard from administration five years ago. The shipyard's main contract since then has been for two ferries, due to serve Arran and the Outer Hebrides.