Centre-right leader Nicolas Sarkozy fulfilled predictions, emerging as top candidate for the second round on 6 May.
Socialist fans of Segolene Royal were relieved at her second-place result after their party's humiliation in 2002.
The French presidential election was billed as one of the least predictable in the nation's recent history.
Segolene Royal - who hopes to become France's first woman president - will vie with Mr Sarkozy in the run-off.
Centrist Francois Bayrou came a strong third - and it is not clear who his supporters will back in the run-off.
Far-right leader Jean-Marie Le Pen lost the 2002 run-off to Jacques Chirac - but this time scored just 11%.
Twelve candidates were vying to succeed President Chirac, who is stepping down after 12 years in office.
Turnout soared to about 84% - just short of a record set in 1962 and far higher than in 2002.
Some 44.5m registered voters were eligible to take part in the election, seen as a turning-point for France.
Polling day for many involved a long wait on a hot April day.