Lothian and Borders Police say they found the drugs in a car in the Borders on Thursday.
The Vauxhall Astra was stopped on the A702 north of West Linton and 100kg of cannabis and 5kg of methedrone were discovered.
The force said the estimated street value of drugs is £200,000.
A 26-year-old man was arrested and charged under the Misuse of Drugs Act. He is due to appear at Edinburgh Sheriff Court on Monday.
A police spokesman said: “This is one of the largest drug recoveries in the force’s history and was made possible thanks to intelligence received from the public.
“Intelligence is essential in combating crime and ensuring that drugs meant for our communities are seized by police.
“Anyone with information relating to drug crime or other criminal activity should contact police.”