Ponzio missed last Saturday's 2-2 draw with a thigh strain but will be back for the return in front of a sold-out crowd at River's Monumental stadium in Buenos Aires, Gallardo said.
"It is always important to have one of your symbols and our captain," the coach told reporters. "(Ponzio) has worked hard these past weeks to get ready. He won't have any problem in playing (a week) on Saturday."
Gallardo was banned from the Bombonera stadium for the first leg after disobeying a suspension in the semi-final against Gremio, but he will be allowed into the Monumental for the return, albeit not on the bench.
Gallardo, who won the Libertadores with River both as a player in 1996 and a manager in 2015, said it was a "horrible" experience watching the action on TV.
He vowed his team would be going all out to win the title for a fourth time in front of their own supporters with away fans banned from all derby matches in Argentina because of fan violence.
"We went and tried to win the game at Boca's ground, we didn't defend with 10 men," Gallardo said. "The idea (in the second leg) is that we will try and impose our way of playing on the match."
The game is the first time Argentina's two biggest clubs have met in the final of what is considered the South American version of Europe's Champions League.
Boca have won the trophy six times, to River's three.
(Reporting by Andrew Downie; Editing by Toby Davis)
