"The Copa America is the oldest worldwide football competition in the world and we are honoured to have received an invitation to compete", said Socceroos coach Graham Arnold.
Scaloni's men beat Chile in the third-place play-off this year, in a game that saw Messi and Gary Medel sent off.
Next year, the tournament will instead see two first round groups of six teams.
The top four teams from each group at the 2020 Copa America qualify for the quarter-finals.
No guest nation has won the Copa, with Mexico coming closest by reaching the final in 1993 and 2001.
Australia will open their tournament against Uruguay on June 13.
Qatar played in the Copa America 2019 and despite losing two of their three matches, proved a tough team, ensuring that they won't be a surprise package in their second appearance in the upcoming matches in 2020.
The June 12-July 12 tournament is the 47th edition of the Copa America, the oldest worldwide competition in world football.