The 22-year-old Barrow-born prop has played 24 games so far this season, and made his debut for the Rhinos in 2011.
He has scored eight tries in 2015 so far.
“I am pleased to have agreed a new four year deal at this great club,” he said.
“At the start of the year I set myself the goal of playing every week, and so far I have only missed two games, although I have to admit that I have surprised myself with how many times I have got over the try line!
“Clearly next season there will be a transition within the side, as a number of players move onto the next stage of their careers.
“That was a major influence for me to sign the new deal. With that transition taking place, it would be silly to look elsewhere, there are some exciting roles to fill, and I am sure there are some exciting times for the youngsters coming through in the next year.
“If you did a head count, we clearly needed to add numbers to the squad for 2016 but I think the recruitment has been excellent and credit for that must go to Brian McDermott and Gary Hetherington.
“I am sure Brian will have some headaches in terms of picking the side but for us as players that is what gets the best out of the side.”
Leeds head coach Brian McDermott is pleased that a player of such clear promise has committed his future to the club.
“I am very pleased that Brad has decided to continue his progression with the Rhinos,” he said.
“The last two seasons have seen Brad establish himself as a regular first team player and he is developing into a tough uncompromising prop.
“He is still relatively young for his position and has his best years ahead of him. But Brad now knows what is needed, not only to play first team but also to play for Leeds Rhinos and the expectancy that comes with that.
“Brad has some very strong leadership qualities that I’m sure will be needed by himself and the team over the next few seasons.”