The giant structure was inaugurated with a firework display during an event that featured lights and musical performances, drawing thousands of people to the lagoon, the Telegraph reported.
This year's theme celebrates the importance of light in people's lives, symbolised by the sun, the moon and the stars.
The 280ft tall structure is illuminated by 3.1 million lights and has been officially certified by the Guinness World Records as the largest of its kind in the world.
The 'tree' has become a major tradition for families from all over the city as well as tourists visiting Rio during Christmas holidays, and its lighting ceremony is the biggest event in the city after Carnival and New Year's Eve.
It will be lit every night until 6 January and will be moved to other locations on the lagoon in the coming weeks so it can be viewed from different parts of the city.(KH)
