In France, the party of far-right leader Marine Le Pen narrowly eclipsed that of centrist President Emmanuel Macron.
And in Italy, the far-right League of Deputy Prime Minister Matteo Salvini won more than a third of the vote, cementing its place as the country's pre-eminent right-wing party.
"The rules are changing in Europe," Salvini declared in Milan yesterday. "A new Europe is born."
But, at least as far as the stewardship of the EU is concerned, the far right will remain on the margins.
That's thanks to the strong showing from liberal, pro-European parties as well as a dramatic surge of votes for the Greens.
A likely alliance between these forces and centrist parties means the EU's agenda could be even more antithetical to that of the Eurosceptics who often hog the headlines.
"As always, a wide variety of voices will be represented in the European Parliament," Stavros Lambrinidis, the EU's top envoy in Washington, said.
"There is a clear majority that supports the EU and that will work as in the past to make our union stronger, more secure, happier and wealthier."
The biggest surprise may be the gains of the Greens.
They finished second in Germany, third in France and gained ground across northern Europe and parts of western Europe.
Their victory in Germany came largely at the expense of the Social Democrats, who, despite years as part of the bulwark of centre-left politics on the continent, have hemorrhaged support to parties on both sides of the political fringe.
Their role over the past decade as the junior partner in a grand coalition led by centre-right Chancellor Angela Merkel exposed them to anti-establishment ire.
That isn't the only reason behind their rise.
"More than a protest vote, Green strength also rests on deep concern in Germany about the state of the planet. German voters told pollsters that the environment was their top concern going into the vote, and that was apparent in the outcome," the Washington Post reported.
"Exit polls in Germany showed the Greens to be the overwhelming top choice for young voters and for first-time voters. The party also did especially well in cities, while taking voters from both the centre-left and the centre-right parties."
It's not an isolated trend.
In neighbouring France, some 25 per cent of voters aged 18-25 voted for the Greens - compared with 15 per cent for the far-right National Rally, whose proponents long claimed they represented the aspirations of the country's youth.
Green parties also did well in Britain, Austria, Sweden, Ireland, Denmark and the Netherlands. From winning 52 seats in the 751-seat European Parliament in 2014, the Greens secured 69 seats this time around, a haul that may make them the fourth largest bloc in the continental assembly.
"This is confirmation for us that the topics we've been working on for years are the topics that matter to the public in their everyday life and for the future of their children," said Sergey Lagodinsky, a newly elected Green member of the European Parliament from Germany. "We had times when we wondered: Is this a fringe agenda? Now we know it's not. It's the mainstream agenda."'
In recent months, massive demonstrations over climate change have rocked European capitals, dwarfing the mobilisations of the continent's far-right.
Fridays for Future - a movement inspired by Swedish teenage activist Greta Thunberg - has seen countless European teenagers walk out of school to protest climate inaction.
It underscores a growing consensus among the next generation of voters that governments must do more to mitigate environmental disaster, and an impatience with political parties that refuse to recognise the urgency of the situation.
Climate change, said an editorial in France's Liberation newspaper, "has become the principal criteria of judging political action in the European Union."
For that reason, it's causing the once-ascendant far-right a headache. "The Greens will destroy this country and our job must and will be to fight the Greens," Alexander Gauland, co-leader of the far-right Alternative for Germany, told reporters.
Gauland's party entered Germany's Bundestag for the first time after elections in 2017 on a platform that inveighed against the spectral threat of immigration and Islam. It doesn't believe that climate change is man-made, a view shared to varying degrees by other far-right parties in Europe as well as US President Donald Trump.
But future generations on both sides of the pond may be more animated by fear of planetary calamity - and may seek to mobilise politics in their countries to better adapt their societies to the changing climate.
That's the bet that both insurgent Democrats are now making in Congress and that jubilant Greens and other progressive factions have made in Europe.
"The Greens represent the only project of the future," French Greens leader Yannick Jadot said yesterday on local television.
To be sure, their appeal remains limited now mostly to Western and Northern Europe's more affluent societies.
But their growing popularity shows that debates over immigration and identity aren't the only existential politics shaping the West.
And that, indeed, there's a collective cause that's worth rallying people around, rather than dividing them.
For European liberals, it's a welcome reckoning.
"Many citizens have mobilised against the dark forces of right-wing populism," wrote French journalist and Guardian columnist Natalie Nougayrède.
"For European citizens, some fundamental values and achievements turned out to be worth cherishing, not throwing away in a fit of anger.
"Perhaps there is more common sense and moderation than we feared in Europe's political landscape. The centre is holding."
