Morris is very highly-rated and made his Boro first-team debut aged just 16 last season.
A host of Premier League clubs including Manchester United, Manchester City, Chelsea and Liverpool were keen to lure him away from The Riverside, but Morris has been persuaded to put pen-to-paper with Boro.
Boro have also handed a three-year contract to striking starlet Bradley Fewster, another England Under-17 international.
Brazilian imports Rafael Pereira and Marcos Rhoden, who have arrived as part of the deal with Juninho's club Ituano, have signed one-year deals.
Fellow Academy graduates Lewis Sirrell and Matthew Waters have signed 12-month contracts.
Boro boss Tony Mowbray told the club's website: "I'd like to congratulate all the players and wish them well in their careers.
"They all know there is a lot of hard work ahead, but they have been given a chance and I'd like to think that's what we do at this club, give good players a chance."
Chief executive Neil Bausor added: "This shows our commitment to the future of the club. It shows we value what we produce and the work put in on many levels.
"We recognise this is just the start of something which will benefit everybody. It's an exciting time in a player's career"