The raids that started at 5 a.m. ET took place at 36 locations around Montreal, the North Shore and the Laurentians, said Const. Franco Di Genova of Laval police.
Police said 40 people have been arrested for trafficking and more arrests are expected.
Tuesday's raids are the result of a nine-month investigation dubbed Project Moisson.
Di Genova said preliminary work indicates the number of pills seized in the raids will rise, but detectives are still "searching different areas of the houses where the drug busts are taking place."
One of the sites raided was a transformation centre in Saint-Hippolyte, where powder was transformed into pills.
Di Genova compared the yield of the police operation to previous busts, including one in 2012 when a total of 105,000 pills were seized.
He said those allegedly involved are part of a well-structured group that dealt with the Mafia, as well as motorcycle and street gangs. The group dealt two kilograms of cocaine a week, and also trafficked GHB, commonly known as the date rape drug, and marijuana, according to Di Genova.
More details will be revealed this afternoon when police hold a news conference.