Ashley has scored 17 goals in 227 appearances for the Reds to date, following his arrival from Aston Villa in the summer of 2011.
During his time at the club so far, the 33-year-old has won five trophies – the Community Shield in 2011/12, the Premier League in 2012/13, the Emirates FA Cup in 2015/16, and the League Cup and UEFA Europa League in 2016/17.
Ole Gunnar Solskjaer told MUTV: ““Since I’ve come into the club, Ashley has been fantastic. His attitude and his experience around the place is vital for us because we have got a young team.
””We’ve got players that need some leaders in the dressing room and Ash is one of them so I’m delighted.”“”