The rugby body said that it was the first prosecution for online hate at the 2023 World Cup and "further cases are pending across five jurisdictions".
The man, identified by Australian media as Aaron Isaia, a youth worker from Brisbane, pleaded guilty to an online harassment charge on Monday and was handed an AUS$1,000 (£522) good behaviour bond.
He will also be banned from all World Rugby events.
"World Rugby welcomes this landmark outcome," chief executive Alan Gilpin said in a statement.
"The vile and toxic abuse is an all-too-common occurrence for many sportsmen and women and public figures.
"We hope that this sends a very strong message to online trolls that such behaviour is totally unacceptable and that the sport and the authorities are prepared to take action."
The New Zealand-born Isaia, 22, sent a television match official (TMO) and his wife threatening and abusive messages via Facebook during the World Cup.
He was tracked down by a World Rugby online abuse programme supporting match officials and their families.
Separately, Wayne Barnes, who refereed the World Cup final between South Africa and New Zealand in Paris, reportedly received death threats afterwards, as did TMO Tom Foley.
