Saudi Arabia will host the WTA Finals for the next three years and offer record prize money of $15.25m (£12.04m).
The event, featuring the top eight singles players and doubles teams of the year, will be the highest-profile tennis tournament held in the country.
The WTA came close to staging the 2023 Finals in Saudi, before going to Cancun in Mexico.
This year's Finals will take place from 2 to 9 November in Riyadh.
The Next Gen ATP Finals, which features the best men under 21, was held in Saudi Arabia last year.