The Italian succeeds Alan Curbishley who resigned last week after claiming the Hammers board were selling players over his head.
But when asked who buys and sells the players, Zola said: "Me! First I'll see the team, see who they are, the make a consideration if something is to be done."
Zola, 42, also insisted he will have no problems working with director of football and compatriot Gianluca Nani.
The former Chelsea star said: "We are a team, GN and the board are part of the team. Once I see how the team is we make plans, whether to buy or sell.
"I have no problem working with a technical director. My job is working on the pitch.
"I'll develop the players, then I'll report to the technical director. He's working with me, not against me. We'll do what's good for the club."