The 18-year-old, who is yet to find the net in League Two since joining in September, has been praised by Southend boss Phil Brown for his contribution this season.
Brown told the club's official website: "It's great news that Cauley will be here with us until the end of the campaign. He's worked extremely hard since joining on loan initially for a month and then a further month.
"As a young striker it's important to get games and goals. Cauley has got a couple in the cup and I'm sure when he does get that first league goal he'll kick on from there.
"Extending this until the end of the season means he can settle here, work hard and improve as a footballer with us."
Woodrow is highly regarded at Fulham.