The 17-year-old put pen to paper at Rockliffe Park earlier this week a month after helping England win the European U-17 Championships in Malta.
He and his team-mates, including Boro Academy team-mate Dael Fry, were later invited to parade their trophy around a packed Wembley Stadium before the senior England team's friendly with Peru.
"These are exciting times for me and I'm delighted to have secured my future here at Boro," says Callum. "I've been with the Academy since I was eight and it means a lot to get this contract.
"We were thrilled to win the European Championships and it was a fantastic moment when we were invited to show the trophy to the crowd at Wembley.
"We really got the feeling that the whole country was behind us. I can't thank everyone enough for the reception they gave us.
"Now it's matter of getting back to club football and trying to build on last season. I'll be concentrating on trying to cement a place in the U-21s and perhaps break into the first-team squad if I can."
Callum was a penalty hero when England beat Holland 4-1 on spot kicks in the final of the Euros. He has become a key member of John Peacock's U-17 squad, captaining his country against Gibraltar last October.
He scored two goals in a 2-2 draw with Portugal in the Algarve tournament last February.