After a brief pause in August when the numbers out of work fell by 2,000, the new figures took the government's main measure of unemployment to its highest level since February 2000.
The increase raises new challenges for the government's stated aim to get unemployment below 9 percent by year end.
Job seekers in all age groups saw their fortunes worsen. An additional 0.6 percent of under 25s were looking for work in September, taking their total to 438,000.
For people over 50, the figure was up 2.1 percent in September and 14.3 percent for the year. 572,000 people in this age group are without jobs.
In an interview with business daily Les Echos, the employment minister Xavier Bertrand said he was "not surprised" by the figures given the "slowdown in economic activity."
"We are not that far away from the 9 percent target," he said, "but who can say exactly what will happen?"
"My priority today is to make sure that job-creating measures are in place."
A planned shake-up of the government agency that handles job seekers, Pôle Emploi, will be announced at the end of November.
"There will be a change of logic," said the minister. "We need to reinforce local teams and free them from certain administrative constraints. Our three objectives will be personalized advice, independent advisers and a reactive approach."