Metron Construction Corp. was originally fined $200,000 in provincial court but in a decision released Wednesday, the Court of Appeal for Ontario boosted that to $750,000.
The four workers who were killed were among six people doing repairs on a high-rise building's balconies using scaffolding that was meant to hold two people collapsed.
The conviction for Metron was the first time in Ontario that the Criminal Code has been used to hold a company responsible for a worker's death.
The Appeal Court said the lower court judge erred by looking at comparable fines under the Occupational Health and Safety Act, rather than the more serious penalties under the Criminal Code.
The Appeal Court said the lower fine was "manifestly unfit" because it failed to convey a message on the importance of worker safety.
"Indeed, some might treat such a fine as simply a cost of doing business," the Appeal Court judges wrote.
"Workers employed by a corporation are entitled to expect higher standards of conduct than that exhibited by the respondent. Denunciation and deterrence should have received greater emphasis. They did not. The sentence was demonstrably unfit."
Alesandrs Bondarevs, Aleksey Blumberg, Vladamir Korostin and Fayzullo Fazilov fell 13 floors to their deaths. The men ranged from 25 to 40 years old and were from Lativa, Uzbekistan and Ukraine.
A fifth worker survived but was seriously injured. A sixth worker, the only one properly wearing a full-body safety harness, was not hurt.
Toxicology tests showed that the men who died all had marijuana in their systems.
As far as the company knew at any given time any worker on scaffolding was secured by a harness, the Appeal Court said. Representatives for Metron did not know why this was not the case on Dec. 24, 2009.
Fazilov was the on-site supervisor and Metron was criminally liable for what the Appeal Court called his "extreme" negligence.
The provincial court judge sentenced the owner of the company, Joel Swartz, to pay $90,000 plus a $22,500 victim surcharge fine for four convictions under the Occupational Health and Safety Act.
Ontario Federation of Labour president Sid Ryan applauded the court's decision.
"You cannot put a price on a life and no financial penalty can bring these workers back or fill the void left in their families, but the magnitude of this fine will send a powerful message to employers that the lives of workers can't be written off as the cost of doing business," Ryan said in a statement.
Project manager Vadim Kazenelson still faces a criminal trial on charges stemming from the deaths.