Police are investigating the theft, which apparently occurred overnight, a police source told AFP.
The 1956 work, "Visage aux mains," one in a series of 20 silver plates by the famous Spanish artist, disappeared from one of the many exhibition halls set up around Miami in parallel to the annual Art Basel festival.
"I've been doing art shows all my life," David Smith, owner of the Amsterdam-based Leslie Smith Gallery, which owned the Picasso work, told the Miami Herald. "I've never, ever had anything stolen."
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The 16.5-inch (40-centimeter) plate, featuring a rudimentary face and hands, had been installed at the Art Miami display on Monday.
According to Smith, in Miami for the art fair, a security guard saw the plate during regular rounds on Thursday night, but when the collector arrived Friday morning, it was gone.
The exhibition hall is guarded 24 hours a day, but there aren't security cameras everywhere.
The plate was the only item to disappear from the gallery, which is exhibiting a number of even more valuable items, including a Picasso ceramic valued at $365,000, Smith said.
But the plate's small size makes it easy to hide, he suggested, adding that the theft had been reported to an international registry of stolen art aimed at blocking black-market sales.
Tens of thousands of collectors, museum curators, art lovers and tourists come to Miami each year for Art Basel, the US installation of a festival created in Switzerland in 1970.
Parallel exhibits, aimed at taking advantage of the influx of art-minded visitors, also spread over the city.
