San Juan del Puerto, Florida, Spanish mission site in Jacksonville, United States.

San Juan del Puerto was a Spanish Franciscan mission on Fort George Island, near the mouth of the St. Johns River in what is now Jacksonville. Founded before 1587 to serve the Saturiwa, a Timucua people, it was organized by dividing them into nine smaller villages. It became one of the three principal missions of the Mocama Province, alongside San Pedro de Mocama on Cumberland Island and Santa Maria de Sena on Amelia Island.

The settlement was founded around 1587 as a Spanish outpost for colonization and converting the Timucua people to Christianity. It was abandoned in 1702 when the community dispersed.

The mission's name, San Juan del Puerto, was given by the Spanish, and the Saturiwa were organised into nine smaller villages around it. After 1650 Guale refugees from the Georgia coast were settled here alongside the Mocama. Father Francisco Pareja taught a writing system he devised for Timucua to some of the Mocama.

The mission site lies on Fort George Island near the mouth of the St. Johns River, within today's Jacksonville; the island is reached by road from the mainland. Nothing in the sources records marked trails, excavations or visitor facilities, so plan around the island's terrain rather than expecting an organized archaeological park.

In 1612 Francisco Pareja, who worked at this mission, printed a catechism in Spanish and Timucua. It is considered the first book printed in an indigenous language of the Americas. The mission was one of three principal missions in the Mocama Province, with San Pedro de Mocama on Cumberland Island and Santa Maria de Sena on Amelia Island.