The pay rise is worth £7m a year to the Spanish goalkeeper and makes him the best-paid goalkeeper in the world.
United's show of faith comes not long after De Gea's proposed move to Real Madrid during the summer fell apart on transfer deadline day.
De Gea was in the Spanish capital as the two clubs thrashed out a deal but the required paperwork was not submitted to the Spanish FA before its deadline.
Speculation will continue to surround the 24-year-old's long-term future, but United have now insured themselves against De Gea leaving the club for free at the end of the season when his previous deal was due to run out.
The bumper salary makes him one of United's top earners and is a further testament to the negotiating powers of "super-agent" Jorge Mendes who is believed to have fallen out with Real Madrid's president Florentino Perez.
De Gea surpasses other well-remunerated stoppers such as Petr Cech on £100,000 a week, Manuel Neuer on £110,000 and Joe Hart on £120,000 a week- who himself was once the highest paid goalkeeper in the world.
It also makes him the joint-third highest paid player in the Premier League, in line with Raheem Sterling and Eden Hazard on a salary of £10.4m a year.