McGuire, who turns 30 next month, had 12 months to run on his current deal but penned a two-year extension on Saturday.
"I am really pleased to get the contract agreed and signed before the start of pre-season," said McGuire, who won his sixth Grand Final with his hometown club last month. "I can now fully focus on getting myself in the best possible shape for a massive season for the Rhinos and myself, with it being my testimonial year."
He added: "I am feeling great at present, having had some time off at the end of the season, and I am raring to go for the start of pre-season training on Monday."
McGuire, who made his debut for the Rhinos in 2001, surpassed his former Leeds team-mate Keith Senior last season to become Super League's all-time leading tryscorer and currently totals 201.
He is fifth in the club's all-time list with 222 tries in all competitions, just six behind Drew Turnball.
Leeds coach Brian McDermott said: "Danny is a unique talent and we are very privileged to have him play his entire career at Leeds Rhinos.
"We all have been guilty over the years of perhaps taking him for granted in terms of what he does for this team because he performs at such a high level every time he steps onto the field.
"However, his value to this team is never underestimated and I am delighted he has agreed a contract extension."