Avarelli was born in Rome and became a judge there. He first took up rudimentary bridge during World War II when more than thirty years old. Along with interests in tennis, riding and motor racing, he was especially noted for "his addiction to gastronomy".
Avarelli was the longtime partner of Giorgio Belladonna using the Roman Club bidding system. They improved the system together and presented it in a book that was published in at least two Italian editions, 1958 and 1969.
Avarelli won 12 world championships, all as one of six players on the Italy open team-of-four.
Runners-up: none. He joined the Italy team after its second-place finish in the 1951 Bermuda Bowl and retired before its double second-place finish in 1976.