"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 today, a day after he oversaw the signing of a warplanes deal with Qatar worth 6.3 billion euros (USD 7 billion).
Fabius said that some of the projects were in the armament sector and "will be finalised in the coming months".
Energy deals -- "mainly in the field of solar power" -- and prospects for nuclear power cooperation are also being discussed, he added.
"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.