"It sounds like a fantastic idea to me," the 56-year-old, who inspired Argentina to World Cup glory in 1986, told reporters at FIFA's Zurich headquarters.
"This will give more possibilities to countries that have never reached that level of competition."
FIFA president Gianni Infantino, who took charge of the scandal-tainted world body last year, has made expanding the World Cup from the current 32 teams the centrepiece of his administration.
But his plans have faced criticism including warnings that it will dilute the quality at football's showcase event.
"The quality will not fall," said Maradona, dripping with sweat after rumbling his way through a mini tournament of former football greats and current executives.
Infantino has been courting support from the game's most powerful figures ahead of Tuesday's meeting.
Among those playing on the snow-lined pitch Monday was UEFA boss Aleksander Ceferin, who has voiced scepticism towards expansion, and CONCACAF chief Victor Montagliani, who is open to a bigger tournament.
Former French international David Trezeguet said more World Cup berths could give "possibilities to countries and especially players who have never experienced this beautiful competition", while acknowledging that details still needed to be worked out.
Among the major concerns from critics is that a longer tournament would increase pressure on an already strained club schedule.
The influential European Clubs Association, led by German great Karl-Heinz Rummenigge, has come out against an enlarged World cup, citing football's overloaded calendar.
Infantino says that money should not drive any decision, but a confidential FIFA report seen by AFP projects that 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.
The influential council will review five proposals on Tuesday: leaving the World Cup unchanged at 32 teams, two proposals for a 40-team competition and two 48-team scenarios.
Infantino is said to be backing a 48-team option with 16 groups of three, which would come into effect for the 2026 competition.
Any decision made Tuesday will have to be approved by FIFA's full 211 members at the body's next congress.