While the centre, liberal and Socialist parties were set to retain a majority in the 720-seat parliament, the vote dealt a domestic blow to the leaders of both France and Germany, raising questions about how the European Union's major powers can drive policy in the bloc.
Making a risky gamble to try to re-establish his authority, Macron called a parliamentary election, with the first round on June 30.
Like Macron, German Chancellor Olaf Scholz also endured a painful night where his Social Democrats scored their worst result ever, suffering at the hands of the mainstream conservatives and hard right Alternative for Germany (AfD).
Meanwhile, Italian Prime Minister Giorgia Meloni saw her position strengthened by her arch-conservative Brothers of Italy group winning the most votes, exit polls showed.
A rightwards shift inside the European Parliament may make it tougher to pass new legislation that might be needed to respond to security challenges, the impact of climate change or industrial competition from China and the United States.
However, exactly how much clout the euro-sceptic nationalist parties will wield will depend on their ability to overcome their differences and work together. They are currently split between two different families, and some parties and lawmakers for now lie outside these groupings.
"ANCHOR OF STABILITY"
The centre-right European People's Party (EPP) will be the biggest political family in the new legislature, gaining five seats to field 189 deputies, a centralised exit poll showed.
In Poland, Prime Minister Donald Tusk's centrist Civic Coalition, a member of the EPP, was set to win the European vote. In Spain as well, the centre-right People's Party, also part of the EPP, came out on top, outperforming Socialist Prime Minister Pedro Sanchez.
Such results were good news for EPP member Ursula von der Leyen who seeks a second five-year term at the helm of the powerful EU executive arm.
And she was quick to present herself as a shield against extremes.
"No majority can be formed without the EPP and together ... We will build a bastion against the extremes from the left and from the right," she told supporters at the EPP's election night event in Brussels.
She added, later in the evening: "But it is also true that extremes and on the left and the right have gained support and this is why the result comes with great responsibility for the parties in the centre."
Von der Leyen may still need support from some right-wing nationalists, such as Meloni's Brothers of Italy to secure a parliamentary majority, giving Meloni and her European Conservative and Reformists (ECR) allies more leverage - which could upset other potential allies.
VOTERS' WORRIES
The centre-left Socialists and Democrats are poised to be the second biggest political family, even as they lost four lawmakers to end up with 135, the exit poll showed.
Political observers attribute the shift to the right to the rise in the cost of living, concerns about migration and the cost of the green transition as well as the war in Ukraine -- worries that nationalist and populist parties have seized on.
"I think a lot of people felt that Europe is doing things not with people, but just doing it on top of people," Greens' lead candidate Bas Eickhout told Reuters in an interview, asked why the far right was doing so well.
"And I think here we need to come up with a credible answer, otherwise, we're only getting further to the far right," he said, after the Greens and liberals lost ground in the election.
Eurosceptic nationalist groups ECR and Identity and Democracy (ID) and hard-right lawmakers not yet affiliated to an EU political family from Germany's AfD secured together 146 seats, a gain of 19, the centralised exit poll showed.
The exit poll projected that pro-European centre-right, centre-left, liberal and Green parties will retain a majority of 460 seats, but one which is slimmed down compared to their 488 in the outgoing chamber of 705 deputies.
Europe's Green parties in particular suffered heavy losses, subsiding to 53 deputies from 71 in the outgoing parliament.
The European Parliament co-decides with the intergovernmental European Council on laws governing the 27-nation bloc of 450 million people.
The exit poll gave the ECR three more deputies than in the last parliament for a total of 72 and the far-right ID group nine more seats for a total of 58.
The number of non-affiliated deputies who may choose to join other groups, including the euro-sceptics, jumped by 33 to 95, the exit poll said.
In Austria, the count of votes cast in polling stations on Sunday plus a projection for postal ballots confirmed the far-right Freedom Party won but by a smaller margin than had been forecast, national broadcaster ORF said.
In the Netherlands, estimates based on most of the votes counted confirmed exit polls that showed a Labour/GreenLeft combination was set to have won eight seats, slightly ahead of the anti-immigration party of Geert Wilders' six seats.
