Maduro announced the expulsions in a televised speech after being officially proclaimed the winner of Sunday's election in the South American nation, AFP reported.
The vote was boycotted by the main opposition parties and condemned by the United States, which denounced it as a "sham."
The Venezuelan president declared US charge d'affaires Todd Robinson and deputy head of mission Brian Naranjo "personae non gratae."
"They must leave the country in 48 hours in protest and in defense of the dignity of the Venezuelan homeland... Enough of conspiracies!" he said.
A State Department official said Washington had "not received notification from the Venezuelan government through diplomatic channels," but that if the expulsions are confirmed, "the United States may take appropriate reciprocal action."
In anticipation that Venezuela's charge d'affaires in Washington, Carlos Ron, would be expulsed, he was appointed vice minister of foreign affairs for North America.
On Monday, US President Donald Trump tightened sanctions against Caracas, making it harder for the government to sell off state assets.
"I repudiate all the sanctions that are sought against the Bolivarian Republic of Venezuela, because they harm it, they generate suffering for the people of Venezuela," Maduro said in the speech.
He promised to present "evidence" that both diplomats were engaged in a political, military and economic "conspiracy."
Robinson denied the allegations.
"We strongly reject the accusations against me and against" Naranjo, he told journalists in the western city of Merida, promising to return there even despite Maduro expulsing him.
Washington and Caracas have not exchanged ambassadors since 2010, and relations between the two countries have been tense since the late leftist president Hugo Chavez, Maduro's mentor, assumed power in 1999.
Maduro was declared the winner with 68 percent of the vote, but with a record abstention rate.
Days before the elections, 11 soldiers were arrested for planning destabilizing actions against Maduro, and they were ordered to prison on Tuesday.
Venezuelans are reeling under a deepening crisis, with hyperinflation projected by the IMF to reach 13,800 percent this year and dire shortages of food and medicine.
The Foreign Ministry earlier lashed out at the US sanctions, accusing Washington of intensifying a "criminal financial and economic blockade," which it called a crime against humanity for impeding "access to essential goods."
It said US policy "promotes hatred, intolerance and political and financial lynching" of Venezuela.
Washington has previously slapped sanctions on the president and his senior aides, and banned US entities from buying any more debt from Caracas or state oil company PDVSA.
The European Union said it was also weighing new sanctions after the election was marred by "irregularities" and failed to meet international standards.