Guaido landed at the country's main airport, about 40 kilometres (25 miles) from Caracas. He said in a tweet he had successfully passed through immigration checks.
"We know the risks that we face, that's never stopped us," the 35-year-old leader of Venezuela's National Assembly said as he moved through a crowd that included several Western ambassadors. The United States and about 50 other countries have recognized Guaido as Venezuela's legitimate leader, arguing that last year's re-election of Maduro was illegitimate because popular opposition candidates were barred from running.
"The regime must understand, the dictatorship must understand... that we're stronger than ever. We'll continue protesting, we'll continue mobilizing," said Guaido, who had ignored an official ban on foreign travel to leave Venezuela, first for Colombia and then elsewhere in Latin America.
Guaido has called for nationwide demonstrations coinciding with his arrival. Thousands of supporters heeded the call, peacefully gathering at a Caracas plaza and in other locations around the country. Some people carried national flags.
Maduro has said he is the target of a U.S.-backed coup plot after the Trump administration joined dozens of other countries in recognizing Guaido as the rightful president of a nation in the midst of a political and humanitarian crisis.
Venezuela's vice president, Delcy Rodriguez, did not directly address a question about whether Guaido faces arrest during a recent interview with Russian state-owned TV channel RT. But she left open the possibility, saying Guaido had broken the law and is "a Venezuelan who conspires with foreign governments to overthrow a constitutional government."
Maduro, meanwhile, has urged Venezuelans to enjoy the carnival season slated for Monday and Tuesday, even though many people don't have the resources to travel to beaches and other holiday spots.
(FRANCE 24 with AFP, AP, REUTERS)