The hardcourt tennis tournament, one of the world's top events outside of the Grand Slams, was scheduled to begin with qualifying on March 23 and run through April 5.
The ATP and WTA earlier wiped out the combined event at Indian Wells, California, which was to have started main-draw play Thursday.
The news came hours after the NBA, including the Miami Heat, halted its season in the wake of the coronavirus pandemic.
"Miami-Dade County is under a state of emergency as we deal with the public health threat of COVID-19," Gimenez said in a statement.
"Although we do not have community spread at this time, we want to take the preemptive steps to keep it that way.
"Therefore, I have decided to suspend the operation of the Miami-Dade County Youth Fair, the Miami Open tennis tournament, the MIA 5K run, and all major events at the American Airlines Arena."
Also axed was a planned stock car race on March 22 at Homestead Miami Speedway, with NASCAR (the National Association for Stock Car Auto Racing) to decide if the race would be conducted without spectators.
"As we move forward together during this time, we will continue to monitor what the World Health Organization has determined is a global pandemic," Gimenez said. "We will constantly evaluate planned mass gatherings as the situation evolves."