The plant has produced its last car and will close today (fri), with the final 955 workers leaving for the last time.
Unions believe 2,500 jobs will be lost because of the closure- both within the company and in the wider auto component sector.
Mr Weatherill says the state government will continue to support those put out of work as they try to find new jobs.
Meanwhile, Holden's chairman, Mark Bernhard, says the closure doesn't mean the company is finished in Australia