The hotel, which will be developed with luxury lifestyle brand Equinox, is the first hotel to be announced as part of the Amaala Marina Village, also designed by Foster + Partners for developer Red Sea Global.
It will have 128 rooms, including two luxury penthouses, and a design that draws on "the stunning natural landscape and traditional architecture style".
Equinox Resort Amaala will also feature a porte-cochère with a circular floating canopy, which was designed to provide a "dramatic entrance" for guests, whether they arrive by car or boat.
The hotel, which will house a magnesium-salt rooftop pool, features four open courtyards that were informed by traditional Saudi Arabian architecture.
These have been designed with water features and landscaping that aims to naturally cool the air.
"Amaala brings the best in health and wellness together in an area of extraordinary natural beauty to offer exceptional and transformative experiences for guests," said Red Sea Global group CEO John Pagano.
"Equinox's unique brand of luxury and fitness is a fantastic fit, allowing visitors to choose seeking self-improvement during their stay, getting back to nature on land or at sea, or simply enjoying quiet moments with loved ones in comfort and privacy," he continued.
Equinox Resort Amaala will be located next to the Marina Village and the Hijaz Cove in Amaala, which is part of Red Sea Global's wider Triple Bay development that will comprise 29 hotels and about 1,200 luxury villas when completed.
Phase 1 is set to be completed in 2024.
Foster + Partners has previously designed the coral-reef-like Marine Institute for Amaala, which will feature a large man-made reef.
The studio has been criticised for its work in Saudi Arabia, which also includes designing an airport for Amaala – a project that was critiqued by climate activist group Architects Climate Action Network. Following the criticism of its aviation projects, Foster + Partners withdrew from the Architects Declare climate group.
The studio is also working on a ring-shaped hotel on stilts in Saudi Arabia for the Red Sea Project, which is also being developed by Red Sea Global.
Saudi Arabia has recently unveiled a number of large-scale designs, including megacity The Line, which will be designed by architects including Morphosis and an octagonal port city that will be created by Danish studio BIG. These are both part of the country's Neom megaproject, which has been criticised by UN experts as three people have reportedly been sentenced to death for opposing the project.