The LLB graduate paired the floor-length dress, designed by Georges Malelu, with red Steve Madden shoes.
Taking to social media, Mswane said she was "so humbled" to be representing the country. "Thank you so much for all the love. Ngiyabonga (thank you)," she wrote.
The founder of the Lalela Foundation arrived in Poland earlier this week for the pageant, which will take place on 15 July.
Upon her arrival, she was welcomed by Minister of Human Settlements Mmamoloko Kubayi, South Africa's ambassador to Poland NJ Mngomezulu, Mpumalanga MEC Human Settlements MEC Speedy Mashilo, and Western Cape MEC for Infrastructure Tertuis Simmers.
"To fly halfway around the world and be welcomed by the smiling faces of my fellow countrymen is something I will hold in my heart as I continue on this journey. Thank you, ambassador, for making me realise that no matter where we are in the world, South Africans will always be united in the spirit of ubuntu," she wrote on social media.