
In a bid to widen the game's global appeal and enrich its coffers, the FIFA panel endorsed a format with 16 groups of three nations, a tweet from FIFA's official account said.
The move represents the first major change to the World Cup since the tournament was boosted from 24 to 32 teams for the 1998 tournament in France.
Critics strongly oppose the move and it was branded a "money grab and power grab" by New FIFA Now, a group campaigning for reform of the scandal-tainted FIFA.
Infantino took over the body 11 months ago with a vow to repair the damage done at the end of Sepp Blatter's tenure by growing football across the globe.
Enlarging the World Cup, the planet's top sporting competition, was the centrepiece of that plan.
Critics say the expanded tournament would dilute the quality of play and overburden already exhausted players.
Football's powerful European Club Association reiterated its opposition, describing the 32-team model as "the perfect formula".
"We understand that this decision has been taken based on political reasons rather than sporting ones and under considerable political pressure, something ECA believes is regrettable," the body which represents European football clubs said in a statement.
Despite the opposition Infantino had in recent weeks voiced confidence that his flagship project would be approved, noting it would improve FIFA's bank account.
And a confidential FIFA report seen by AFP projects a 48-team tournament would bring a cash boost of $640 million (605 million euros) above projected revenues for next year's finals in Russia.
But Infantino has also argued that more World Cup berths would help serve football's interest by boosting "inclusion" in the "biggest social and sporting event".