The digital clothes, which were informed by Balenciaga's previous collections, were created for four in-game characters.
The collaboration followed the release of Afterworld: The Age of Tomorrow, in December 2020, a video game developed by Epic Games to showcase Balenciaga's Autumn Winter 2021 collection.
"Our partnership with Epic didn't start with Fortnite, actually," said Balenciaga's creative director Demna Gvasalia.
"It started with our own first video game, Afterworld, which we built using Unreal Engine to debut our Fall 2021 collection."
"From [Afterworld: The Age of Tomorrow], we have continued to be inspired by the creativity of Unreal and Fortnite communities," Gvasalia said.
"It made total sense, to me, that we collaborate further by creating these authentic Balenciaga looks for Fortnite and a new physical Fortnite clothing series for our stores."
The digital clothes feature the Autumn Winter 2021 medieval, armour-style pieces, as well as shredded jeans with tracksuit lining, and an animal striped look from its Spring 2020 collection.
In game-weaponry was also given a high-fashion update in form of the brand's iconic accessories.
Sock-style Speed trainers were transformed into a range of pickaxes and the brand's Hourglass bag was modified to be used as a glider.
"Fashion has a long history in the Fortnite community, where players have the agency to show up however they want in our world," said Epic Games president Adam Sussman.
"Self-expression is one of the things that makes Fortnite so unique, and there couldn't be a better first fashion partner than Balenciaga to bring their authentic designs and trendsetting culture to millions of players around the world."
A virtual store, that reflects the design of physical Balenciaga locations, will appear in Fortnite's battle royale mode in a location aptly named Retail Row where players can purchase the garments.
A limited-edition run of physical garments will be available that feature the Fortnite logo across staple Balenciaga items of clothing including, hoodies, denim jackets and button-down shirts.
The in-game garments were created through existing 3D scans of Balenciaga's designs. The Fortnite team then recreated and modified the garments for the game with a "Fortnite spin".
The game developers behind Fortnite and Unreal Engine explained that virtual and physical worlds are becoming increasingly blurred.
"In embracing cutting-edge technologies, Balenciaga has been empowered to court a new digital-native audience, unconstrained by the limits of either world," said Unreal Engine.
Earlier this year, Gucci released digital trainers that people can "wear" in augmented reality and in photographs for social media.
In 2019, Louis Vuitton released a video game titled Endless Runner which was informed by its Autumn Winter 2019 show.