Sakho was heavily linked with an exit during the summer but a move failed to materialise, with the striker still part of Slaven Bilic's plans.
The Senegal international is yet to start a Premier League game this season but has managed one goal in six substitute appearances, and Zabaleta feels the forward can play a key role going forward.
"Diafra can have a big impact for us because he’s a great player, but it is all about confidence," Zabaleta told the club's official website.
"He's not been playing much in the Premier League aside from coming on for a few minutes, and his only starts have been in the Carabao Cup.
"This is what you expect from players like this who, even if they are not starting the games, they come on and give 100 per cent, even if it is only for ten minutes. He did that against Swansea, so I’m very pleased for him."
Sakho scored the winner in the 1-0 win over Swansea and will be hoping to be included in the matchday squad to face Burnley at Turf Moor on Saturday.