When data for the country's overseas territories was included, the second-quarter rate came to 10.2 percent, the national statistics office Insee said, a level last seen in 1999.
A total of 2.8 million people were registered as looking for work in the eurozone's second biggest economy.
On a 12-month basis, the second-quarter increase was 0.6 percent, Insee said.
Unemployment among young people aged 15 to 24 increased by an even faster rate, gaining 0.3 percent on the month and by 0.8 percent on the year to reach 22.7 percent
In a general economic report in June, Insee forecast that unemployment would rise to 9.9 percent of the workforce in mainland France, this year, and 10.3 percent when overseas territories were taken into account.