He suffered a career-threatening eye injury which kept him sidelined for most of the 2005/6 season, but returned to play a central role in United's Premier League title wins in 2007 and 2008, as well as last season's Champions League triumph.
"It's great to sign a new deal, last season was fantastic but you always want to achieve more and with this team we are capable of doing just that," Scholes told United's official website.
Like Scholes, Fletcher has been at Old Trafford for his entire career, making his debut in March 2003 at the age of 19.
Fletcher has never established himself in Ferguson's first-choice side, but he has become a key member of the Scotland team, winning 36 caps.
He was linked with a move to Everton or Birmingham over the summer, but opted to fight for his place at Old Trafford.
"When you play at such a great club with a great team you always want to be a part of that," he said after signing his new deal.
"The spirit here is amazing and I am happy that I can play my part in achieving more success."
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