The crash happened around 6 p.m. EST when Kingston drove his jet ski into a bridge connecting Palm Island to the MacArthur Causeway.
Kingston and a female passenger were rushed to Jackson Memorial Hospital. Reports say he may be in critical condition.
The 21-year-old Miami-born singer gained fame in 2007 with his single "Beautiful Girls."
Palm Island is a private residential neighborhood in Miami Beach only accessible by bridge.
The cause of the crash is still under investigation.
TMZ is reporting that alcohol is not believed to be a factor.