New back-to-fun rules at the park include temperature controls at the entrance, mandatory use of face masks, markers on the ground to help enforce social distancing and posters thanking the public for their help "during this unprecedented time."
Universal Orlando is only reopening at 35 percent capacity and has launched a system of virtual lines in which space can be reserved, to avoid queues and crowds.
Visitors arrive at Universal Studios theme park on the first day of reopening after the shutdown. AFP
Terrence Wilson, 19, was happy with the result. "There's not a lot of people. I can get on all the rides without having to wait 40 minutes or an hour" he told the Orlando Sentinel.
On Monday, the Legoland Florida Park opened in the city of Winter Haven, while SeaWorld in Orlando is scheduled to open on June 10.
The largest of Orlando's parks, Walt Disney World, will open on July 11.
That day the park's Magic Kingdom and Animal Kingdom sections will begin operating, while EPCOT and Hollywood Studios will follow suit on July 15.
Orlando is home to most of the state's theme parks and every year welcomes millions of tourists from all over the world.