The company with the highest number of convictions was Steel NZ Ltd, in Manukau, which was convicted on six health and safety charges relating to four incidents.
Two workers suffered injuries to their fingers, one worker had part of a finger amputated and one had his foot broken by a piece of falling steel.
The company, which failed to report the incidents, was fined $237,500 in total.
A woman in the human resources department said the company did not want to comment.
Other companies, including Alliance Group, Carter Holt Harvey, Taylor Preston, Transfield Services (NZ) and Winstone Pulp International, had up to three convictions,.
Seven companies had incident in workers died. They were Fonterra, C3 Ltd, Carter Holt Harvey, Fulton Hogan, Hawkins Construction, Serv-Ag Ltd and Transpacific Industries Group (NZ).
Other incidents included a man who lost a finger as he tried to clear a cookie dough cutter at Griffins Foods, and another worker who injured his fingers when they became stuck in a conveyor.
Griffins said the safety of its 1,000 workers at three Auckland facilities was its highest business priority and the company invested in safety practices after incidents in 2009 and 2011.
Council of Trade Unions president Helen Kelly was shocked by the figures.
"It's too much. Anybody being prosecuted is too much, they've already injured somebody."
Under the Health and Safety in Employment Act, ministry inspectors can take businesses to court over failure to take practicable steps to achieve a safe workplace.
The offence carries a penalty of up to $250,000.
If the offender has knowledge beforehand that what they were doing is reasonably likely to cause someone serious harm, they face a maximum fine of up to $500,000 and can be imprisoned for two years.
The court looks separately at whether victims should receive reparation for emotional harm.
But the rules will get tougher from December when the Government's Working Safer reforms - due in part to the recommendations of a taskforce partially in response to the Pike River disaster - come into effect.
A person who engages in reckless conduct which puts a worker at risk of injury or death will face a maximum penalty of $600,000 and/or five years' imprisonment, or $3 million for a company.
In the past 10 years, fines totalling $21.8 million have been imposed on companies under the act.
Ms Kelly said the Government changes would hopefully reduce the number of injuries and deaths.
"An organisation that's being prosecuted six times is going to find themselves under the pump in terms of much higher fines, the potential for jail," she said.
"In the end they're going to have to be watched, the dangerous companies watched and prioritised.
"We think they are very, very positive changes ... tightening up worker rights in terms of health and safety, bringing in higher penalties must be the response to dangerous work."
She said there would be "a hell of a lot of companies" that were dangerous but had not been prosecuted.
The Opposition has called for a charge of corporate manslaughter to be introduced into the act, which Ms Kelly supported.
MBIE general manager health and safety investigations Brett Murray said repeat offending was evidence there were systemic issues.
"A company which has six convictions against its name raises the immediate question of how much that company values its workers and the level of commitment its management team has towards providing a safe and healthy work environment."
Workplaces and prosecutions
Workplaces that have had one or more prosecutions against them for injuries or deaths in the past five years to January 2013
• Six convictions: Kiwi Steel NZ
• Three convictions: Alliance Group, Carter Holt Harvey, Taylor Preston, Winstone Pulp International, Transfield Services (NZ) Ltd
• Two convictions: Aquaheat Industries, Fonterra, Fulton Hogan, George Grant Engineering, Goodman Fielder, Griffins Foods, Hawkins Construction, Lean Meats Oamaru, Ecowise, Silver Fern Farms, Sleepyhead, Transpacific Industries Group (NZ) Ltd, Visy Board (NZ)
• One conviction: C3 Ltd
• No convictions: Serv-Ag Ltd (charges were withdrawn and dismissed)
