Craig Douglas Dieffenbach, 61, owned the Seattle Cannabis Cooperative, which had locations in Rainier Valley and Greenwood.
He pleaded guilty in August to conspiracy to distribute marijuana and conspiracy to commit money laundering, according to U.S. Attorney Jenny A. Durkan.
Prosecutors say Dieffenbach and his co-owner billed their business as a cooperative, but were actually running a large-scale drug dealing operation.
"We have made clear that truly sick people and their caregivers will not be targets of our enforcement efforts," Durkan said in a Friday news release. "This defendant was neither. A green cross in the front window does not grant a license to sell pounds of drugs out the back door."
Dieffenbach admits to operating the store for profit and selling large amounts of pot to people who didn't have medical marijuana cards, according to prosecutors. Prosecutors also say co-owner Jing Jing Mo admitted she tried to sell 25 pounds of marijuana to be distributed throughout the country.
The pair also admitted to laundering money from their pot sales and using the money to build grow rooms in their homes.
"Marijuana traffickers continue to have a stranglehold on this state," DEA agent Matthew G. Barnes said in a Friday news release. "DEA will continue to do what it can to loosen their grip."
Once he's released from prison, Dieffenbach will spend four years on supervised release. Mo, who also pleaded guilty, will be sentenced next month.