A new owner is expected to takeover the car parts factory, Empire Rubber, in Bendigo, this week.
Indian company Mothersun Sumi will formally take control, when a new collective agreement for workers is ratified on Thursday.
About 120 people will lose their jobs.
Antony Thow, from the National Union of Workers (NUW), says Mothersun will retain about 100 full time jobs and employ another 40 casuals.
"NUW members had to make concessions in the collective agreement but they were happy to do so if it meant saving jobs and the union is certainly happy to back-up that decision," he said.
"Nobody likes losing conditions but if it means jobs are saved for the benefit of the economy and the community, the NUW is pleased to do that."