The companies have the same sole director, Sizhang Guo.
Quality Kitchens NZ was ordered to pay reparations of $21,828.89 and Quality Construction NZ was ordered to pay reparations of $30,083.84.
By law employers must actively manage risks to ensure workers stay safe, according to WorkSafe New Zealand.
"This case is concerning because less than four months earlier, WorkSafe issued Quality Kitchens a improvement notice requiring it to implement a workplace hazard management and control system and it had not done so when these incidents occurred," WorkSafe chief inspector Steve Kelly said.
"There are two employees who've suffered serious injuries because this employer had not implemented any systems to identify and manage workplace risks, nor had the employer formally trained the two workers on how to safely operate the equipment - that is unacceptable."