The Microsilk fabric eventually breaks down back into the environment, making the dress fully biodegradable, Adidas claims.
While fabrics such as wool or cotton are often labelled as biodegradable, the chemical treatments they undergo to be made into garments can slow down the break-down process or stop it altogether.
"Fashion is one of the most harmful industries to the environment," said McCartney.
"We can't wait any longer to search for answers and alternatives. By creating a truly open approach to solving the problem of textile waste, we can help empower the industry at large to bring more sustainable practices into reality."
To create Microsilk, Bolt Threads studied the silk made by argiope bruennichi – a type of orb-weaver spider that commonly spins its own web – then recreated a version of the proteins in a laboratory.
In order to do so, scientists at the startup bioengineered genes in the lab and implanted them in yeast.
Together with sugar and water, the yeast produces protein through fermentation. Liquid silk proteins are then extracted and spun into yarn to weave for garments.
Microsilk is still in the research and development phase and doesn't have the statistics to compare its water usage with other fabrics, but by using plants that can be regrown Bolt Threads claims it is more sustainable than petroleum-based fibres such as polyester.
The material was mixed with a cellulose-blended yarn to make the prototype dress.
In an exclusive interview with Dezeen, Stella McCartney warned that designers "aren't taking responsibility" for the environmental damage caused by the fashion industry.
"We need to impose new laws on designers because sadly people aren't taking responsibility, and there is no incentive to encourage them," she said.
Meanwhile, Dharan Kirupanantham, leader of Adidas' eco-innovation programme told Dezeen that the sportswear brand is embracing the circular economy.
"It just makes sense," he said. "It's common sense to the industry, and us. That's how we envisage the future."