At the 2012 Summer Olympics in London, Stylianou qualified only for the 200 m freestyle in a B-standard entry time of 2:00.88. She challenged seven other swimmers on the second heat, including four-time Olympian Hanna-Maria Seppälä of Finland and former Olympic champion Camelia Potec of Romania. Stylianou raced to fourth place by more than half a second (0.50) behind Mexico's Liliana Ibanez, outside her entry time of 2:01.87. Stylianou failed to advance into the semifinals, as she matched her overall position from Beijing in the preliminary heats.