By Agence France-Presse
Spencer, a leader of the so-called "alt-right" movement, is due to give a speech Thursday at the University of Florida in Gainesville, a town of some 130,000.
Saying there was an "imminent" threat of a potential emergency as a result, Scott explained that the emergency declaration will ensure that security forces have all the necessary resources at their disposition.
"We live in a country where everyone has the right to voice their opinion, however, we have zero tolerance for violence and public safety is always our number one priority," Scott said, adding that local authorities had requested the extra help.
"This executive order is an additional step to ensure that the University of Florida and the entire community is prepared so everyone can stay safe."
Spencer was involved in and spoke at a white nationalist rally in Charlottesville, Virginia in August that triggered a weekend of clashes. A 32-year-old woman was killed when a car plowed into counter-protesters, and two police officers died in a helicopter crash as they were responding to the violence.
The University of Florida agreed to host Spencer in the name of free speech, but indicated he was not invited to give the talk.
The 39-year-old white supremacist's group paid $10,564 to rent the space, which will go toward some $500,000 the school is expected to pay to boost campus security.
A group of students early Monday protested Spencer's planned appearance, asking the school to scrap his talk.
"We encourage you to speak up with your voices in support of our proudly diverse community and the values of this institution," said Chief Linda Stump-Kurnick, assistant vice president of public and environmental safety at the school.
"We also encourage you to avoid the event. Don't let the University of Florida be defined by Richard Spencer."
According to the Southern Poverty Law Center, which monitors US hate groups, Spencer "advocates for an Aryan homeland for the supposedly dispossessed white race and calls for 'peaceful ethnic cleansing' to halt the 'deconstruction' of European culture."