After an eight-year absence, Horky competed only in the men's 4×200 m freestyle relay, and served as a senior captain for the Czech swimming team at the 2004 Summer Olympics in Athens. Teaming with Michal Rubáček, Květoslav Svoboda, and Martin Škacha in heat two, Horky swam a third leg and recorded a split of 1:53.29, but the Czechs settled only for seventh place and thirteenth overall in a final time of 7:26.26.