Speaking in a sun-flooded Saint Peter's Square at the end of his weekly Sunday prayer, the pontiff said the day highlighted both the importance of independent journalism and the growing threats faced by reporters.
"Today we celebrate World Press Freedom Day ... unfortunately, this right is often violated, sometimes in blatant ways, sometimes in more hidden forms," he said.
The Pope urged the faithful to remember journalists and reporters who have lost their lives pursuing the truth, particularly in areas afflicted by conflicts.
"We remember the many journalists and reporters who have been victims of war and violence," the Pope said.
World Press Freedom Day, sponsored by United Nations cultural agency UNESCO and observed on May 3, is intended as a show of support for media organisations that come under pressure or censorship and as an opportunity to commemorate journalists who have died in the line of duty.
In past speeches, the leader of the Catholic Church has described journalism as a pillar of society and democracy, with information a public good that must be safeguarded and defended against manipulation.
He has often thanked reporters for sharing the truth, saying that doing their job could never be considered a crime, and has frequently called for the release of journalists who have been unfairly detained or prosecuted.