"Thanks to this electronic device, I signed up as a simple pilgrim," Francis said, declaring himself the first person registered for the next edition of the Youth Day celebration while flanked by two Polish youths.
The next edition of the global meeting of Catholic youths will be held in July 2016 in Krakow, Poland. The last one was held in Rio de Janeiro in 2013, shortly after Francis' election as pope.
Before digitally signing up for the event, the pope appealed for the release of Italian Jesuit priest Paola Dall'Oglio, who was kidnapped in Syria two years ago.
Francis also called for "renewed engagement by local and international authorities" to secure the release of all hostages from captivity.
Next year's event will be the 31st edition of World Youth Day which was instigated in Rome in 1986 by pope John Paul II, the first Polish pontiff who also served as Archbishop of Krakow. It has since been held in countries on four continents.