Young, who earns around £120,000-a-week at Old Trafford, has been rewarded following some fine performances last term.
The 29-year-old has impressed Louis Van Gaal with his versatility – being able to play on either wing or as a wingback.
Young is also looking to reclaim his place in the England squad and has not given up hope of a recall in the future.
The player had looked like he would be moved on when van Gaal took charge of the club last summer.
Instead, Young has flourished; playing a key role in the second half of last season and earning praise from fans and pundits alike.
Despite the £25m arrival of Memphis Depay and Angel di Maria’s determination to improve at Old Trafford, van Gaal has tied down Young to a long-term deal. There is a question mark over whether or not he will start for United next season, but the manager must have a plan for him and having decided to keep him in the squad.