Data compiler IHS Markit said its final purchasing managers' index rose to 51.9 from 50.6 in May, reaching its highest point since September as export orders rose despite flaring global trade tensions.
The reading was marginally lower than a preliminary reading of 52.0, but it was firmly above the 50-point line dividing expansions in activity from contractions.
A breakdown of the data showed that new export orders returned to growth in June, rising at the fastest pace in a year with firms mentioning higher orders from Asia, the United States, Italy, Switzerland and Spain.
"When explaining stronger performances, panellists often commented on an improvement in demand conditions," IHS Markit economist Eliot Kerr said.
"Such a trend points to a sustained rise in orders and firms responded by increasing both employment and purchasing activity," he added.
France is increasingly standing out for the modest upturn in its manufacturing activity, which contrasts with downturns in the sector in most other euro zone countries, including regional powerhouse Germany.
In France, the sector is less dependent on demand from China than in Germany, helping to reduce the impact of the current downturn in the world's second-biggest economy.