Alena's modeling career started at the age of 15. Five years later, Alena was first runner-up of Miss Czech Republic 1998 and her country's representative at Miss World 1998 where she placed fourth in the finals. She started her career as a model in 2002. Alena was chosen by the Italian comedian Giorgio Panariello to co-host his own prime-time TV show Torno Sabato. Alena has been featured on the covers of several magazines including Penthouse Europe, Playboy Europe, Spy, Extreme and Quo. In 2005, Alena was chosen to pose in Max Calendar.
Alena was married to Italian national football goalkeeper Gianluigi Buffon. They have a son named Louis Thomas Buffon, who was born on 28 December 2007. Their second son, David Lee was born on 1 November 2009, in Milano, Italy. In May 2014 Buffon announced his separation from Seredova. She has a sister named Eliška, who is also a model. Her mother's name is Jitka Šeredová.
Alena co-owns the Italian clothing-line Baci e Abbracci together with Buffon's former national teammate, Christian Vieri.