More than 4,000 soldiers were sent to the exclusive ski resort, where heads of state and government mixed with business moguls in a forum that wrapped up on Saturday.
Twelve soldiers assigned to guard the high-profile gathering of the world's rich and powerful tested positive for cannabis and five had used cocaine, according to Swiss media reports, which quoted an army spokesman.
"Our soldiers gave an exemplary performance...The few regrettable cases of drug consumption should not tarnish the overall positive impression," said Jean-Marc Halter, divisional commander of the Davos deployment.
Military police using sniffer dogs discovered that one of the soldiers had more than three grammes of cocaine in his possession.
That soldier was sent home and will face criminal charges, Swiss media have said, quoting an army spokesman.
The other troops who tested positive for cocaine were also sent home and will face sanctions, while those who had only smoked cannabis were allowed to remain in Davos.