Ross Dunkley, 60, has long had links with the media industry across Southeast Asia, co-founding English language newspaper The Myanmar Times when the country was in the tight grip of a military dictatorship.
He also used to be a co-owner of Cambodia's Phnom Penh Post.
Police arrested him, his business partner John McKenzie and seven Myanmar nationals during a June 2018 raid on his home in the commercial capital Yangon.
Officers uncovered a stash of crystal methamphetamine, low-grade “ya bah” pills, three opium cakes, marijuana and a small amount of heroin, police said.
One man and one woman, who were working as house helpers for Dunkley, were later released.
“Ross Dunkley and John McKenzie are sentenced to 13 years,” judge Myint Myint Maw told Yangon’s Western District court yesterday.
Five Myanmar women also on trial broke down in tears as they were each sentenced to 11 years, while watching relatives shouted out in anger.
Dunkley appeared shaken and declined to speak to reporters as he was led away from the court room.
All defendants had denied the charges and it is not yet clear if any will appeal.
Myanmar is now believed to be the largest producer of methamphetamine in the world in a shadowy, multi-billion dollar industry.
Crystal meth pumped out from labs in eastern Shan state is trafficked as far away as Tokyo, Seoul and Sydney.
Ya bah pills, made of cheap methamphetamine, are meanwhile scooped up by users across Thailand, Bangladesh and Myanmar at rock-bottom prices.
Last year’s raid was Dunkley's second run-in with Myanmar authorities.
In 2011 he was sentenced to a month in prison for the assault of a woman at a Yangon nightclub, though the court allowed him to walk free after taking into account time already served.