Wood has been in fantastic form in south London, scoring seven times since joining Kenny Jackett's side in September.
Jackett told Sky Sports News that Wood has become a key part of his side in a short space of time.
He said: "We've been very pleased with Chris, he's worked hard in the group and if as a centre-forward you can get in the habit of popping up with a winner, that's great.
"We've been very pleased and are delighted to keep him until January."
The New Zealand international helped stretch Millwall's unbeaten run to 10 games earlier today by making the breakthrough late on in a 1-0 win over Leeds United.