The Socialists won 314 of the 577 seats in the National Assembly, the Parliament’s lower chamber. The majority threshold is of 289 seats.
This is a historic victory for the Socialists, who together with their Green and leftist allies, are expected to control 341 deputies.
The conservative UMP party of former President Nicolas Sarkozy will have 194 MPs, down from 313 they won in the 2007 election.
The French Senate has been dominated by the Socialists since September 2011 and they also control most of the country's regions.
The victory was overshadowed by the defeat of Socialist candidate Ségolène Royal, who was hoping to become speaker of the National Assembly. Royal was beaten in the La Rochelle constituency by a dissident Socialist candidate, Olivier Falorni, who refused to withdraw in her favour.
The defeat of Royal, Hollande's former companion, comes as an embarrassment to the French president whose new partner, Valérie Trierweiler, tweeted her support for Falorni before the election. The incident unleashed sarcastic comments about the failure of the new head of state to keep his private life under control.
Far-right enters Parliament
In another twist, the far-right National Front entered parliament for the first time since the mid-1980s, winning two seats.
Marion Maréchal-Le Pen, niece of Marine Le Pen and granddaughter of party founder Jean-Marie Le Pen, beat a centre-right rival in the southeastern town of Carpentras. The other newly elected National Front lawmaker is lawyer Gilbert Collard, who was chairman of Marine Le Pen’s support committee.
Another highlight is the defeat of leftist leader Jean-Luc Mélenchon, who failed in his attempt to beat Marine Le Pen in the constituency of Pas de Calais in the first round. In the second round, Le Pen herself was beaten by Socialist Philippe Kemel, who won 50.11%, 118 votes more than the far-right leader.
In keeping with tradition after legislative elections, France’s Socialist-led government resident today (18 June).
Hollande’s office indicated that he had immediately re-appointed Prime Minister Jean-Marc Ayrault and asked him to form a new government, which is expected to be nearly identical to the outgoing cabinet.
Impact on the European Parliament
The French election will also have a direct impact on the composition of the European Parliament and other EU institutions.
In the Socialist ranks, Stéphane Le Foll, agriculture minister, who was elected in his Sarthe constituency, will leave the European Parliament, where he will be replaced by Isabelle Thomas. And MEP Kader Arif, appointed minister in charge of the veterans from the anti-Nazi resistance, will be replaced by Eric Andrieu.
Socialist MEP Estelle Grelier, who won in the Seine Maritime constituency, will leave the European Parliament, where she will be replaced by Jean-Louis Cottigny.
On the centre-right, MEP Damien Abad, elected in the Ain constituency, will be replaced in the European Parliament by Karine Fenocchi.
Another French politician working in Brussels may be tempted by a national career. Philip Cordery, secretary-general of the Party of European Socialists, was elected with 53% in the Benelux constituency, defeating UMP candidate Marie-Anne Montchamp.