"If concluded, these 20 projects would be worth tens of billions of euros," Fabius told reporters in Riyadh.
French President Francois Hollande is also in Saudi Arabia to attend a Gulf leaders' summit on Tuesday, a day after he oversaw the signing of a warplanes deal with Qatar worth 6.3 billion euros ($7 billion).
Fabius said that some of the projects were in the armament sector and "will be finalised in the coming months".
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Energy deals -- "mainly in the field of solar power" -- and prospects for nuclear power cooperation are also being discussed, he added.
Fabius said that agreements on transport, including civil aviation, and other infrastructure projects were on the table, as well as health services.
"These are extremely important prospects that show that the partnership is moving at a new speed with some concrete results," the minister said.
King Salman acceded the throne in January following the death of his half-brother king Abdullah.