When centrist Emmanuel Macron was swept to power in presidential elections last May, his big platform was a reform of France’s rigid labour laws.
But his popularity has since waned, and the measures to be revealed on Thursday will be a big test for his presidency.
He is facing mass protests next month, although one of the biggest unions has decided it will not take part.
The leader of Force Ouvrière (FO) praised the government’s “real consultation” and “social dialogue”.
Jean-Claude Mailly argued that the Macron team had backed away from “ultraliberal” reforms, justifying his union’s decision not to take part in a day of street demonstrations on 12 September.
France’s biggest private sector union, the CFDT, is also seen as unlikely to join the protests, which are being spearheaded by the far-left CGT. Further demonstrations are promised by far-left leader Jean-Luc Mélenchon later in the month.
Mr Macron wants to free up the French economy by making it easier for employers to hire and fire staff, and negotiate working conditions.
An earlier attempt to modernise France’s labour laws by François Hollande’s Socialist government largely failed in the face of left-wing opposition. However, Mr Macron has already won parliamentary backing to push these reforms through by decree.
The package of dozens of measures, to be detailed in a 200-page document, has been drawn up by Labour Minister Muriel Pénicaud and will be presented to the unions and other social partners at 10:00 (08:00 GMT) on Thursday, before it is made public by Prime Minister Edouard Philippe.
Among the reforms, businesses are expected to be offered more flexibility by shifting their negotiations with unions from a national to a company level. Companies with fewer than 50 employees would be able to circumvent negotiating deals with the unions, according to French reports.
Another key measure is a cap on damages that can be awarded to workers who are laid off. However, the cap has been increased from an initial proposal during the three months of consultations with the unions.
President Macron has pledged to reduce unemployment from 9.5% of the workforce now to 7% by 2022. But last week, on a visit to Romania, he complained that France was not a “reformable country… because French men and women hate reform”. He quickly went on to explain that what France needed was “transformation” rather than reform.
Mr Macron has seen his popularity slide dramatically since he came to power on 7 May. A poll on 27 August suggested his approval ratings had fallen from 57% in July to 40%.
A separate poll on Wednesday showed that while nine out of 10 French people agreed that their country’s labour code had to be reformed, 60% were worried about the Macron plan.