Carrisi was born in Rome on November 29, 1970, the eldest daughter of Albano Carrisi and Romina Power. Her maternal grandparents are American actor Tyrone Power and Mexican actress Linda Christian.
In 1983, she appeared alongside her parents in the Italian film Champagne in paradiso. Later on, she was the letter-turner on La Ruota Della Fortuna, the Italian version of Wheel of Fortune. She envisaged for herself a career as a novelist, studying literature at King's College London, where she received the highest marks in her year.
During her studies, she began to entertain the idea of traveling the world solo with nothing but a backpack and her journal. She decided to take a break from studying and returned to Italy where she sold all her belongings in order to pay for the voyage. She began in South America. After having spent a few months in Belize, she decided to leave the day after Christmas 1993 by bus to New Orleans, Louisiana. Her brother Yari, also an experienced traveler, had decided to surprise his sister by visiting her that Christmas. He arrived on a rainy 27 December in the village of Hopkins, going door to door in search for her, only to find that the day before, she had hopped on a bus heading to Mexico. Unfortunately, he arrived 24 hours too late for she was already heading to New Orleans, where she disappeared on January 6, 1994.
Ylenia was last seen in the French Quarter area sometime during the month. Police efforts to find her did not yield any result. At the time of her disappearance, Ylenia was staying in the LeDale Hotel with African-American street musician Alexander Masakela, twenty years her senior. Masakela was arrested on January 31 on an unrelated charge but eventually released for lack of evidence to connect him to Ylenia's disappearance.
In relation to her disappearance, a security guard testified that he saw a woman vaguely matching her description jump into the Mississippi River saying the words "I belong into water". A Coast Guard search turned up no sign of the young woman's body, which may have been washed out to sea. In any case, it has never been established that the person was Ylenia. In 1996, two years after her disappearance, an unspecified caller assured emphatically that Ylenia was still alive but her whereabouts were unknown.
Carrisi's parents last heard from their daughter on New Year's Eve. They reported her missing on January 18. In November 2006, Albano stated for the first time that he believed the security guard's story. In January 2013 he requested the declaration of the presumed death of his daughter. She was reportedly discovered in June 2011 in a monastery in the United States. Her father dismissed the report as "shameful speculation containing not a bit of truth.". The mystery has yet to be solved...