Mardini was 18 years old at the time of the 2016 Olympics. On 6 August, she swam in the first round of the women's 100 meters butterfly; and won her heat in a time of 1 minute and 9.21 seconds. However, only the top 16 overall were to advance to the semifinals, and her overall ranking was 40th. Next for her was the women's 100 meters freestyle on 10 August. She was 7th in her heat with a time of 1 minute and 4.66 seconds, and, as usual, the top 16 overall fastest times made the semifinals. Her overall placement with that time was 45th, so she was eliminated.