William Watson bought the property where his house in downtown St. Augustine later stood in 1779 from James Penman, a British attorney and friend of Andrew Turnbull who left East Florida following a series of disputes with then Governor Patrick Tonyn.

The Watson House became the property of Martín Mateo Hernández, a young Minorcan immigrant under the Father's care.

[3] After the heirs of Martín Hernández died in 1802, the Watson House became part of the Spanish Military Hospital complex on what is now Aviles Street, serving as the apothecary.

[4] Sanborn Fire Insurance Maps show the lot empty from 1894 to 1899, when a stable building was constructed on the property.

The Historic St. Augustine Preservation Board reconstructed the Watson House in 1968 as an example of British Period architecture.