The pilot whale was discovered on Monday in a canal in the southern province of Songkhla and received treatment from a team of veterinarians.
The department's chief theorized that the whale had mistaken the plastic bags for food, but after eating them had become "sick and unable to hunt for food", Reuters reports.
The whale spit out five plastic bags on Friday and later died, the Marine and Coastal Resources Department said on its website at the weekend.
Each year, Thailand puts over one million pounds of garbage into the ocean, making it one of the biggest offenders on earth, along with China, Indonesia, the Philippines and Vietnam.
Marine biologist Thon Thamrongnawasawat told Agence France-Presse the bags would have made it impossible for the whale to eat nutritional food.
"If you have 80 plastic bags in your stomach, you die", he said, adding that at least 300 marine animals, including pilot whales, sea turtles and dolphins, die annually after ingesting plastic in Thai waters.
More than 5 trillion pieces of trash - and counting - are in the world's oceans, according to a 2014 study. We have filled our oceans with a lot of fucking plastic.
Upsetting photographs show the shocking result of pollution on a whale that starved to death because it had swallowed 80 plastic bags.
"Because he's a whale he can travel around the world".