The ex-England international, who has brilliantly switched from scrum-half to full-back over the last two seasons, would have been out of contract at Headingley at the end of 2022.
However, Myler, 31, will now be with the blue and amber until at least the end of 2024.
Having joined from Catalans Dragons in 2018, he could see out his career in Leeds colours and will have played more at the Rhinos than at any other club.
“I am really pleased to have got my new deal finalised and I am looking forward to the next three years,” said the ex-Warrington Wolves star.
“There is an incredible family atmosphere at the club and I can not wait to be part of what this group can achieve in the next few years. I have been fortunate to play for a number of clubs in my career but I feel like I have found a home here at Leeds.
“Richard Agar has done a tremendous job of moving the club forward and I am excited to see the strength in depth we have this season within our squad.
“The club have shown their intent by bringing in world-class talent and we have got an exciting crop of young players.”
Myler’s positional switch – he won the last of his eight
England caps as a scrum-half in 2018 - came after young full-back Jack Walker suffered a serious foot injury and also following No7 Luke Gale’s arrival from Castleford Tigers.
Walker, 22, is expected to be fit for the start of the new season when Leeds start against Warrington in the first live Betfred Super League game broadcast on Channel 4 on February 12.
Myler said: “When you look across our squad, everyone can do a job for the team and I am looking forward to playing my part.
“There is competition for every position in the side and that brings out the best in all of us.
“It is great to see Jack Walker back in full training after his injury setbacks in the last few years and we have also got a number of other players who can play full-back too so we both know we need to be at our best in every session.”
Myler won the Lance Todd Trophy as man-of-the-match when Rhinos lifted the Challenge Cup at Wembley last year and he hopes to earn more silverware in the coming years.
Leeds head coach Agar is delighted to see such an influential player commit to the club in the long-term.
“I am really pleased for Richie that he has agreed this new deal,” he said.
“A couple of seasons ago, he found himself at a crossroads and he has reinvented himself and taken on a number of roles within our squad.
“He is an important player for us at full-back, as we saw with his Lance Todd trophy-winning performance in 2020, but he also brings versatility in a number of key positions.
“He has evolved into a great team player and a real clubman.
“He has settled into life at the Rhinos. I know he calls Leeds his home now and this is a just reward for his hard work and effort.”