Weah, 21, came on in the second half for Canadian forward Jonathan David.
It was the second time Weah won the Trophée des champions. He won in 2018, starting and scoring the final goal for PSG in a 4-0 win over Monaco in Shenzhen, China.
He also won the Ligue 1 title with PSG in 2018 and 2019 and Scottish league and cup titles with Celtic in 2019.
Weah was loaned by PSG to Celtic midway through the 2018-19 season and sold to Lille the next summer.
-- Brenden Aaronson started and contributed an assist in Red Bull Salzburg's 7-1 win over Ried in the Austrian Bundesliga.
-- Christian Cappis scored his first goal for his new Danish club, Brondby, in its 2-2 tie against Vejle in the SuperLiga.