The 20-year-old was contracted until the end of the season but has won an extension after impressing new boss Steve Evans.
"I’m delighted; committing my future here is something I’ve looked forward to doing," Coyle said on the official website.
"I got a one-year contract in the summer and my aim was to always extend that by doing well and impressing.
"Hopefully I would then get handed a longer deal and I’m delighted that’s happened."
Coyle is yet to make a senior appearance for Leeds but captains the Under-21 side.
Evans believes the right-back has a bright future and is plotting the next stages of his development.
"We need to get him playing football," Evans said. "Whether that’s sending him out for a little while... We’re looking at all the options now.
"He’s training with the first team every day now and in two-and-a-half to three weeks, I’ve seen him get much, much better."