Pakistani designer Maheen Khan is behind the ensemble, with Kate having opted to wear Khanâ€™s pieces several times already this tour.
Earlier today 37-year-old Kate sported a scarf by Khan, and on day two of the tour, she modelled a cobalt design of hers.
Khan has been working in the fashion industry since 1972 and has done embroidery for multiple films and television shows, including Snow White and the Huntsman and The Jewel in the Crown.
A shalwar kameez is the national dress of Pakistan: the shalwar refers to the trousers, which are often loose and baggy, while the kameez refers to a long-line shirt.
Kate covered her head for the visit to the Badshani Mosque with a traditional dupatta, which is a shawl-like scarf commonly worn as part of a shalwar kameez.
For the visit, Kate also shunned shoes and opted to go barefoot.
While it is not compulsory to cover your head or remove shoes while visiting mosques, it is advised to dress as modestly and as respectfully as possible.
Kate visited the mosque, an iconic Islamic landmark in Lahore, alongside her husband Prince William.
Kate followed in the footsteps of her late mother-in-law Princess Diana , who visited the site in 1991 and also chose to cover her head in respect.
A visit to the Badshani Mosque was also included in the 2006 royal tour of the Prince of Wales and Duchess of Cornwall.
Scroll through our gallery above for more pictures of the Duke and Duchess of Cambridge in Pakistan.