Prosecutors say 38-year-old Jason Loken thought he was selling six pounds of pot to a prostitute last summer when he was confronted by two robbers who bound him and stole his marijuana, hash oil and guns.
Loken freed himself, grabbed another gun and fired a dozen shots at the robbers in the residential neighborhood.
He hit one of the robbers and their driver, who didn't know she was involved in a drug rip-off.
Seattle U.S. Attorney Jenny Durkan says authorities are seeing an increase in marijuana-related violence.
Washington state has legalized possession of marijuana, but state licensed stores aren't expected to open until July.
One of the robbers, Melvin Charles Slaughter, was sentenced to 14 years in prison, while the other, Ferdinand Clay, faces sentencing next month.