The Japanese high street brand will launch the range in store from August 22nd, featuring printed silk dresses and headscarves, bright tunics and several designs from Birtwell's archives.
Birtwell told Vogue.co.uk "I had such a good time with my first season that I was delighted when Uniqlo asked me to do a second. They have been a wonderful company to work for so it was an easy decision for me to make."
Prices range from 12.90 pounds for a Heattech T-shirt to 69.90 pounds for a long-sleeved silk dress.
Birtwell, who's partner in life and business was Ossie Clark, was a renowned designer in the 60s with her distinctive couture prints and designs. In 2006 Birtwell collaborated with Topshop and she has previously designed for British accessories brand Radley.
Images: Uniqlo x Celia Birtwell