Agreement was finally reached late last night over a deal that will keep the Belgium-born wide-man at Old Trafford until 2018.
Whilst manager David Moyes is understandably delighted at the news, it also marks a personal triumph for Woodward, who came under such scrutiny after United's failure to secure the targets they attempted to sign during the summer transfer window.
Press Association Sport understands Woodward had to navigate a delicate set of discussions, and fend off a number of illegal approaches to keep one of the most sought-after young players in Europe.
With memories still fresh over the exit of midfielder Paul Pogba, who has made such a positive impact at Juventus, it could be argued Woodward has scored a moral victory over Gill.
It was certainly an enlightening experience for Woodward considering the number of middle-men, claiming to represent other clubs, who emerged at various stages of the negotiating process.
An Old Trafford source said: "It has not been the easiest deal to put together.
"There has been a lot of diplomacy involved and whilst the club is obviously delighted to have secured Adnan's services for an additional five years, it is terrific news for Ed too.
"A lot of questions have been asked about him but he has been working on this deal for months and he deserves a lot of credit for bringing it to a successful conclusion."
The 18-year-old, whose international future remains open to debate amid speculation he is open to the possibility of playing for England once he qualifies on residency grounds in 2016, has already made a big impression this season, scoring both goals in a 2-1 win at Sunderland earlier this month.
"It's a great thrill to be able to sign for Manchester United," said Januzaj. "Since arriving here I have always felt like this was the right club for me.
"This season has been great for me - going on the pre-season tour, making my debut in the Community Shield win at Wembley and then breaking into the team at Sunderland - it's like a dream.
"I want to work hard now and establish myself as a Manchester United player."
Januzaj could even make his Champions League debut on Wednesday, when United face Real Sociedad.
He was registered earlier this week after United delayed completing the paperwork deliberately so he could be added to the B List, meaning he did not have to be part of the official 25-man squad Moyes submitted to UEFA at the start of the tournament.
After collecting four points from their opening two games, the Sociedad encounter represents a chance to consolidate their position - the La Liga outfit have surprisingly lost both their matches so far.
European exposure would represent another step forward in Januzaj's career which, for the short-term at least, will be spent at Old Trafford.
"I'm delighted that Adnan has committed his future to United," said Moyes.
"He is an outstanding talent and has impressed me consistently since I came to United in July.
"His balance, poise and ability to beat players is truly exceptional for a boy of his age.
"It's great that he recognises that this club, with its tradition for developing young players and giving them a chance on the biggest stage, is the best place for him to be."