The supposed craft was caught on camera, with footage showing the mysterious lights blinking in the night sky.
It was seen in the popular resort of Buzios, an area of southern Brazil renowned for its idyllic beaches.
The clip shows a line of flashing lights, which appear to be connected and moving in tandem.
Buzios rose to popularity among tourists in 1964 when the French actress Brigitte Bardot was pictured strolling along its beaches.
Valentina, an Argentinian tourist who posted one of the videos on social media, accompanied it with the caption: “This was shocking, they were not drones, nor fireworks, and they were there for 15 minutes crossing the sky in Buzios from one side to another.”
Local media have labelled the lights UFOs, but Brazilian authorities are yet to comment on the incident.
One witness said: “In Buenos Aires a green light was seen doing the same thing.”
The peninsula is home to over 20 beaches and is especially popular among tourists from the city of Rio de Janeiro and Argentina.