The half-back had just one year left on his existing deal with the Super League champions.
The 29-year-old told the club's website: "I am feeling great at present and I am really pleased to get the contract agreed and signed before the start of pre-season.
"Leeds is my club and I am proud to have played my entire career for the Rhinos.
"We have had some great times in recent years but when you look at the young guys who are coming into the team you can see that there are definitely more special moments to come."
McGuire has won six Super League Grand Finals with Leeds.