The request was made in an open letter to FIFA president Gianni Infantino at CONMEBOL's annual conference in Buenos Aires.
"As we think big, and because we want justice, because we want you and all our companions to want to think big, I am asking that the 2022 World Cup is played with 48 teams," CONMEBOL president Alejandro Dominguez said.
FIFA agreed in January last year to expand the World Cup from its current 32 teams to 48 teams in 2026.
CONMEBOL currently get five guaranteed spots for the 32-team World Cup, and that number will rise to six - or 60 percent of all member nations - at a 48-team tournament.
The 2022 World Cup will be hosted in Qatar, the first time the tournament will take place in the Middle East.
The host of 2026 World Cup will be decided in June, with Morocco hoping to overcome the joint bid from the United States, Mexico and Canada.
(Reporting by Andrew Downie; Editing by Christian Radnedge)
