President Nicolas Maduro said the diplomats would have 48 hours to leave the country, saying "Yankees, go home!"
Maduro claimed to be having evidence that the trio participated in a power-grid sabotage in September and bribed Venezuelan companies to cut down production.
The diplomats expelled have been named as Kelly Keiderling - the charge d'affaires and the most senior US diplomats in Caracas - David Moo and Elizabeth Hoffman.
The US and Venezuela have been without ambassadors in each other's capitals since 2010.
Maduro said: Out of Venezuela! Yankees go home
"We completely reject the Venezuelan government's allegations of US government involvement in any type of conspiracy to destabilize the Venezuela government,'' the US embassy said in a statement, adding that it had not yet been officially notified of the Venezuelan government's decision to expel the three diplomats.
Maduro made the announcement during an official ceremony at the city of Santa Ana.
"Out of Venezuela! Yankees go home! Enough of abuse against the dignity of a peace-loving nation," he said.