| State: | FL |
| Type: | SR |
| Route: | 312 |
| Maint: | FDOT |
| Map Custom: | yes |
| Length Mi: | 3.836 |
| Length Round: | 3 |
| Direction A: | West |
| Terminus A: | near St. Augustine |
| Junction: |
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| Direction B: | East |
| Terminus B: | in St. Augustine |
| Counties: | St. Johns |
| Previous Type: | US |
| Previous Route: | 301 |
| Next Type: | US |
| Next Route: | 319 |
State Road 312 (SR 312) is a 3.8adj=midNaNadj=mid state highway serving St. Augustine, Florida in the United States. Its western terminus is at SR 207, and its eastern terminus is at County Road A1A (CR A1A) near St. Augustine Beach.
State Road 312 begins at the intersection between SR 207 and SR 312, where SR 207 continues northeast into central St. Augustine. About 0.4miles east of the western terminus, SR 312 passes over the Florida East Coast Railway main line via an overpass. 1miles from the western terminus, SR 312 intersects U.S. Route 1 (US 1), with SR 312 continuing a few blocks east through St. Augustine until the Mickler-O'Connell Bridge over the Intracoastal Waterway. At the waterway, SR 312 enters St. Augustine city limits, where it intersects SR A1A. Continuing east, the state highway ends at the point CR A1A transitions to the roadway to continue heading east.