Saint John the Baptist is the patron saint of the Commonwealth of Puerto Rico and its capital city, San Juan. In 1521, the island was given its formal name, “San Juan Bautista de Puerto Rico”, following the custom of christening a town with its formal name and the name which Christopher Columbus had originally given the island. The names “San Juan Bautista” and “Puerto Rico” were eventually used in reference to both city and island, leading to a reversal in terminology by most inhabitants largely due to a cartographic error. By 1746, the city’s name (“Puerto Rico”) had become that of the entire island, while the name for the island (“San Juan Bautista”) had become that of the city. The official motto of Puerto Rico also references the saint: Joannes Est Nomen Eius (Latin for “his name is John”, from Luke 1:63).

The Church of Jesus Christ of Latter-Day Saints teaches that John the Baptist appeared on the banks of the Susquehanna River near Harmony Township, Susquehanna County, Pennsylvania, as a resurrected being to Joseph Smith and Oliver Cowdery on 15 May 1829, and ordained them to the Aaronic priesthood. According to the Church’s dispensational view of religious history, John’s ministry has operated in three dispensations: he was the last of the prophets under the law of Moses; he was the first of the New Testament prophets; and he was sent to restore the Aaronic priesthood in our day (the dispensation of the fulness of times). Latter-day Saints believe John’s ministry was foretold by two prophets whose teachings are included in the Book of Mormon: Lehi and his son Nephi.

A crypt and relics said to be John’s and mentioned in 11th- and 16th-century manuscripts, were discovered in 1969 during restoration of the Church of St. Macarius at the Monastery of Saint Macarius the Great in Scetes, Egypt.

Several different locations claim to possess the severed head of John the Baptist. A Shrine of Saint John the Baptist (Nabi Yahya in Arabic) is found inside the Umayyad Mosque in Damascus. The place was visited by Pope John Paul II in 2001.

In 2010, bones were discovered in the ruins of a Bulgarian church in the St. John the Forerunner Monastery (4th–17th centuries) on the Black Sea island of Sveti Ivan (Saint John) and two years later, after DNA and radio carbon testing proved the bones belonged to a Middle Eastern man who lived in the 1st century AD, scientists said that the remains could conceivably have belonged to John the Baptist. The remains, found in a reliquarium, are presently kept in the Sts. Cyril and Methodius Cathedral in Sozopol.