The 21-year-old has agreed a season-long move to become the 15th summer signing at Tynecastle Park in a huge coup for the club. He has also extended his Old Trafford contact by another year until 2020.
Mitchell played 11 times in maroon last season after arriving on loan in January and became a firm favourite with supporters. The Hearts management made his return one of their top priorities this summer and finally reached an agreement with counterparts in Manchester over the weekend.
Mitchell should go straight into the squad for this Saturday’s Premiership match with St Mirren as Hearts try to continue their 100 per cent start to the league campaign.