From May 2022 to April 2023, dengue virus serotype 3 (DENV-3) was identified in 601 travel-associated and 61 locally acquired cases in Florida, USA. All 203 sequenced genomes belonged to the same genotype III lineage, indicating potential transmission chains. Most locally acquired cases occurred shortly after introduction, with limited sustained transmission. DENV is not endemic in the continental US, and most cases are travel-associated. In Florida, DENV infections are primarily reported among travelers, with limited outbreaks in Monroe and Martin counties. The Florida Department of Health (FDOH) identified an increase in travel-associated DENV infections, particularly from Cuba, in early 2022. A DENV-3 outbreak was reported in Cuba in July 2022, and similar increases were documented in other countries in the Americas. Miami-Dade County issued a mosquito-borne illness advisory after the first locally acquired DENV infection in 2022. The study analyzed epidemiologic features, genomic sequences, and possible transmission trees. DENV-3 was the most frequently identified serotype, with 601 travel-associated and 61 locally acquired cases. Most cases were White and Hispanic or Latino. Travel-associated cases had a median age of 52 years, with 51% male and 49% female, and most traveled from Cuba. Locally acquired cases had a median age of 54 years, with 67% male and 33% female, and nearly all were in Miami-Dade County. Genomic characterization revealed that DENV-3 genomes were classified as genotype III and clustered within the novel American II lineage, indicating a spreading lineage across the Americas. Phylogenetic analysis showed low genomic diversity and frequent importation events without sustained local transmission. A graph-based model suggested limited local transmission, with most travel-associated cases not leading to further transmission. The study highlights the importance of international surveillance and healthcare provider awareness to strengthen preparedness and response to future introductions.From May 2022 to April 2023, dengue virus serotype 3 (DENV-3) was identified in 601 travel-associated and 61 locally acquired cases in Florida, USA. All 203 sequenced genomes belonged to the same genotype III lineage, indicating potential transmission chains. Most locally acquired cases occurred shortly after introduction, with limited sustained transmission. DENV is not endemic in the continental US, and most cases are travel-associated. In Florida, DENV infections are primarily reported among travelers, with limited outbreaks in Monroe and Martin counties. The Florida Department of Health (FDOH) identified an increase in travel-associated DENV infections, particularly from Cuba, in early 2022. A DENV-3 outbreak was reported in Cuba in July 2022, and similar increases were documented in other countries in the Americas. Miami-Dade County issued a mosquito-borne illness advisory after the first locally acquired DENV infection in 2022. The study analyzed epidemiologic features, genomic sequences, and possible transmission trees. DENV-3 was the most frequently identified serotype, with 601 travel-associated and 61 locally acquired cases. Most cases were White and Hispanic or Latino. Travel-associated cases had a median age of 52 years, with 51% male and 49% female, and most traveled from Cuba. Locally acquired cases had a median age of 54 years, with 67% male and 33% female, and nearly all were in Miami-Dade County. Genomic characterization revealed that DENV-3 genomes were classified as genotype III and clustered within the novel American II lineage, indicating a spreading lineage across the Americas. Phylogenetic analysis showed low genomic diversity and frequent importation events without sustained local transmission. A graph-based model suggested limited local transmission, with most travel-associated cases not leading to further transmission. The study highlights the importance of international surveillance and healthcare provider awareness to strengthen preparedness and response to future introductions.