Francois Hollande became the first Socialist French President in 17 years by defeating the incumbent Nicolas Sarkozy in the Sunday run-off.
According to the early estimates based on the partial results, Hollande secured around 52 per cent vote against his rival Sarkozy's 47 per cent, reported the BBC.
There was around 80 per cent of polling.
"This is a great happiness. It ends 17 years of rule by the right at the Elysee Palace, 17 years of political right and within these 17 years, the parenthesis of Sarkozyism who has accumulated regressions social and democratic," Belgian newspaper Le Soir quoted Socialist Party's Benoit Hamon as saying.
Polling closed at 20:00 at big cities in France and the first set of results were announced shortly after that.
Scores of enthusiastic socialist supporters were seen flooding Hollande's hometown Tulle and also in the party headquarters in Paris. The supporters were seen celebrating well before the actual results came out.
The opinions polls had predicted that Hollande would win with around 53 per cent of the votes.
The French began voting for their next president on Sunday morning. Voting had begun a day earlier in the overseas territories of France.
Sarkozy's conservative government becomes the 11th European government ousted from power in recent times.
The governments of Spain, Italy, Britain, Ireland, Greece, Portugal, Denmark and Finland have all been toppled in recent years due to an escalating economic crisis.
The election results are expected to influence everything: France's economy in the Eurozone to French troops' stay in Afghanistan.
The French have been blaming Sarkozy for the higher unemployment and the general economic crisis in the country.
Earlier, Marine Le Pen failed to extend her support to any of the candidates, which crushed the odds of Sarkozy winning the election. Le Pen secured close to 20 per cent of the votes in the first round.
The first round of elections on 22 April gave Hollande a one per cent lead over Sarkozy.