The coordinated move by France, Spain, Germany, Britain, Portugal, Sweden, Denmark, Austria and the Netherlands on Monday came a day after the expiry of an eight-day ultimatum for Maduro to call a new election.
Latvia and Lithuania also lined up behind Guaido, the self-declared interim president who has the support of the United States and many South American nations.
The European countries urged Guaido to hold free and fair elections as soon as possible.
Italy blocked an EU statement saying the group recognised Guaido, the Reuters news agency reported citing diplomatic sources.
"We are working for the return of full democracy in Venezuela: human rights, elections and no more political prisoners," Spanish Prime Minister Pedro Sanchez said in a televised announcement.
He said Spain, which has a large Venezuelan community, is also working on a humanitarian aid programme for Venezuela, where shortages of basic items are acute. Critics of Maduro blame the Venezuelan government's mismanagement for the lack of food and medical supplies.
German Chancellor Angela Merkel said during a visit to Japan on Monday that Guaido "is the legitimate interim president".
In a Twitter post, French President Emmanuel Macron declared Venezuelans have "the right to express themselves freely and democratically", and said France recognises Guaido as an "acting president to implement an electoral process".
Swedish Foreign Minister Margot Wallstrom said the presidential election that brought Maduro to power last year was neither free nor fair and told Swedish broadcaster SVT that Venezuelans "now must get new, free and fair elections instead".
'Interference'
Jeremy Hunt, Britain's foreign secretary, said Venezuelans had suffered enough.
"The oppression of the illegitimate, kleptocratic Maduro regime must end," he said.
Maduro, 56, a former union leader, bus driver and foreign minister, replaced Hugo Chavez as the president in 2013 after his death from cancer. But he has presided over an economic collapse and the exodus of three million Venezuelans.
Russia responded to the European move by accusing the group of meddling in Venezuela's domestic affairs.
"Attempts to legitimise usurped power" constituted "interference in Venezuela's internal affairs", Dmitry Peskov, spokesman for President Vladimir Putin, told reporters.
Such interference, he added, could not facilitate the "peaceful, effective and lasting settlement of the crisis the Venezuelans are going through".
Russia and China, who have poured billions of dollars of investment and loans into Venezuela, are supporting Maduro in an extension of their geopolitical tussle with the US.
Maduro rejects European demands
Maduro, meanwhile, showed no signs of caving in to the pressure and lashed out at the EU and the US, which has imposed sanctions on Venezuelan oil exports.
In a live addess on state television, Maduro said he refuses ultimatums from any country. He was especially harsh on Spain's Sanchez, who he said would have "blood on his hands" if a coup is carried out against him.
"If one day there is a coup, if one day there is a gringo military intervention, your hands will be stained with blood, Mr Pedro Sanchez," Maduro said.
President Donald Trump told US media on Sunday that deploying troops to Venezuela was "an option".
Maduro blames Washington for an "economic war" and coup pretensions aimed at controlling oil. Venezuela has the largest reserves in the world, but production has plunged under Maduro's rule.
Critics say incompetent policies and corruption have impoverished a once-wealthy nation while dissent has been brutally crushed.
Although the military's high ranks have continued to reiterate their support for Maduro, on Saturday, a senior air force general disavowed the leader in a video circulated online. He claimed that "90 percent of the armed forces don't support the dictator".
General Francisco Yanez is the first active Venezuelan general to recognise Guaido since he proclaimed himself president on January 23.
Guaido still has no control over state institutions or any functions of day-to-day governance.
He has sent letters to Russia and China saying a change of government would be in the best interests of both countries.