Environment Minister Albert Jacob said the Liberal National Government had launched the Regional Roadside Litter Prevention Project along three litter hotspots - the Brand, Great Eastern and Forrest highways.
The $185,000 project, supported by the Keep Australia Beautiful Council (WA) and Main Roads Western Australia, will run until the end of December 2016.
"The project is centred on the 'WA Naturally Thanks You' message and will encourage people to do the right thing with their rubbish by promoting a sense of personal responsibility," Mr Jacob said.
"Everyone is capable of making a difference and I'm confident thanking people in advance for doing the right thing will help change the habit of roadside littering. This initiative, together with the State Government's recently announced container deposit scheme, will make a big difference in WA."
Results from the 2015-16 National Litter Index confirmed that roadsides continue to attract high volumes of litter and are the source of most of the litter found in WA.
As part of the project, there will be signs on the highways and at rest stop bins. Complimentary litter bags will also be available at 20 roadhouses along these routes. The Keep Australia Beautiful Council will also survey drivers at the roadhouses on their reactions to littering.
Transport Minister Dean Nalder said these roads were subject to heavy traffic and had historically been popular spots for littering.
"I'm hopeful that, as the amount of rubbish in these areas reduces, people will be encouraged to keep them clean and litter free," Mr Nalder said.