The Botafumeiro is a large censer made of silver-plated brass that is 1.60 meters tall and weighs 62 kg when empty. The present Botafumeiro, which weighs 62 kg, is heavier than its predecessor, which weighed 60 kg, due to the addition of a silver bath in 2006. The synthetic rope measuring 65 meters in length, 5 centimeters in diameter, and weighing 90 kilograms is what holds it to the transept of the cathedral. Ropes were traditionally woven from esparto grass or hemp. A group of eight men, called tiraboleiros, first push it to get it moving, and then each pulls on one end of the rope to get up to speed; the Botafumeiro is filled with about 40 kg of charcoal and incense (weighing more than 100 kg at the beginning of its movements), then tied with strong knots to a long rope that goes to the roof of the building, and moves through the nave of the church via a pulley mechanism. Moving from the Azabachera door to the Plateras door in the cathedral's transept, the Botafumeiro may attain speeds of up to 68 kilometers per hour while describing an arc of 65 meters at a maximum height of 21 meters (an angle of 82.o). There are 17 full paths needed to get to the top.

According to legend, the censer was first used in the cathedral of Santiago in the 11th century to perfume the temple and get rid of the foul stench left by the pilgrims, who were often dirty, smelly, and sick. In 1200, the original system of pulleys was replaced with rollers that allowed it to move laterally, increasing its range to about 150 cm (the maximum distance the rope would allow). In 1400, French King Louis XI gave the cathedral money to replace the old censer, but the project wasn't finished until 1554. The Botafumeiro's current rolling mechanism was put in place in 1604.

The original silver censer from the War of Independence was stolen by Napoleon's troops in April 1809; the current silver censer was crafted by goldsmith José Losada in 1851.

The Compostelan censer, or Botafumeiro, has great symbolic significance in Spain. In 1993, the design of the 5 peseta coin featured an etching of the Botafumeiro.