First, a run-down of the particulars:
- Due to potential metric conversion issues and weight class changes, a limit of 161 pounds is observed for this list.
- Inception of the championship occurred on 1/13/1990, the first fight between two top fighters that resulted in a clear #1.
- Sporadic periods of inactivity were observed throughout the first half of the lineage. Clear “top contender” matches took place to determine the next champion.
Your current lineal Lightweight champion is Islam Makhachev
The full history is below. Note, the colored backgrounds indicate a title change.
MMA Lightweight Lineal Championship History
| Date | Champion | Outcome | Challenger | Notes |
| 1990-01-13 | Yuichi Watanabe | WIN | Kazuhiro Sakamoto | |
| 1990-05-12 | Yuji Ito | WIN | Yuichi Watanabe | |
| 1992-03-27 | Tomohiro Tanaka | WIN | Yuji Ito | |
| 1992-07-23 | Naoki Sakurada | WIN | Tomohiro Tanaka | Sakurada leaves division. |
| 1994-05-06 | Yuki Nakai | WIN | Kyuhei Ueno | Vacant title. Top-contender matchup. |
| 1994-11-07 | Yuki Nakai | WIN | Kazuhiro Kusayanagi | |
| 1995-01-21 | Yuki Nakai | WIN | Hiroaki Matsutani | Nakai leaves division. |
| 1995-04-01 | Luiz Fraga | WIN | Leandro Heck Gembo | Vacant title. Top-contender matchup. |
| 1995-07-05 | Luiz Fraga | WIN | Marcos Vieira | |
| 1995-07-05 | Luiz Fraga | WIN | Marcelo Romano | |
| 1995-07-05 | Wander Braga | WIN | Luiz Fraga | |
| 1995-09-12 | Wander Braga | WIN | Leandro Heck Gembo | |
| 1996-11-01 | Wander Braga | WIN | Johnny Eduardo | |
| 1996-11-01 | Wander Braga | WIN | Ailton dos Santos | |
| 1998-06-12 | Wander Braga | WIN | Euclide Ourico | |
| 1998-06-12 | Wander Braga | WIN | Marco Antonio | |
| 1998-06-12 | Wander Braga | WIN | Milton de Castro | Braga goes inactive. |
| 1999-09-05 | Caol Uno | WIN | Din Thomas | Vacant title. Top-contender matchup. |
| 1999-12-11 | Caol Uno | WIN | Andre Pedeneiras | |
| 2000-04-02 | Caol Uno | WIN | B.J. Penn | |
| 2000-08-27 | Marcio Ramos Barbosa | WIN | Caol Uno | |
| 2000-12-17 | Dokonjonosuke Mishima | WIN | Marcio Ramos Barbosa | |
| 2001-12-16 | Dokonjonosuke Mishima | WIN | Ryan Bow | |
| 2002-02-11 | Dokonjonosuke Mishima | WIN | Ben Thomas | |
| 2002-06-29 | Dokonjonosuke Mishima | WIN | Iran Mascarenhas | |
| 2002-09-07 | Dokonjonosuke Mishima | WIN | Takafumi Ito | |
| 2002-12-14 | Takanori Gomi | WIN | Dokonjonosuke Mishima | |
| 2003-02-23 | Takanori Gomi | WIN | Nick Ertl | |
| 2003-08-10 | Joachim Hansen | WIN | Takanori Gomi | |
| 2003-12-14 | Vitor Ribeiro | WIN | Joachim Hansen | |
| 2004-07-09 | Vitor Ribeiro | WIN | Mitsuhiro Ishida | |
| 2004-12-14 | Tatsuya Kawajiri | WIN | Vitor Ribeiro | |
| 2005-04-23 | Tatsuya Kawajiri | WIN | Jani Lax | |
| 2005-05-22 | Tatsuya Kawajiri | WIN | In Seok Kim | |
| 2005-07-17 | Tatsuya Kawajiri | WIN | Luiz Firmino | |
| 2005-09-25 | Takanori Gomi | WIN | Tatsuya Kawajiri | |
| 2005-09-25 | Takanori Gomi | WIN | Luiz Azeredo | |
| 2005-12-31 | Takanori Gomi | WIN | Hayato Sakurai | |
| 2006-04-02 | Marcus Aurelio | WIN | Takanori Gomi | |
| 2006-06-04 | Mitsuhiro Ishida | WIN | Marcus Aurelio | |
| 2006-08-26 | Mitsuhiro Ishida | WIN | Cristiano Marcello | |
| 2006-11-05 | Mitsuhiro Ishida | WIN | David Bielkheden | |
| 2006-12-31 | Takanori Gomi | WIN | Mitsuhiro Ishida | Gomi’s 2nd reign. |
| 2007-02-24 | Takanori Gomi | NC | Nick Diaz | |
| 2008-03-05 | Takanori Gomi | WIN | Duane Ludwig | |
| 2008-08-24 | Takanori Gomi | WIN | Seung Hwan Bang | |
| 2008-11-01 | Sergey Golyaev | WIN | Takanori Gomi | |
| 2009-01-04 | Eiji Mitsuoka | WIN | Sergey Golyaev | |
| 2009-08-02 | Eiji Mitsuoka | WIN | Clay French | |
| 2009-11-07 | Kazunori Yokota | WIN | Eiji Mitsuoka | |
| 2009-12-31 | Tatsuya Kawajiri | WIN | Kazunori Yokota | |
| 2010-07-10 | Shinya Aoki | WIN | Tatsuya Kawajiri | |
| 2010-09-25 | Shinya Aoki | WIN | Marcus Aurelio | |
| 2010-10-24 | Shinya Aoki | WIN | Yokthai Sithoar | |
| 2011-04-09 | Shinya Aoki | WIN | Lyle Beerbohm | |
| 2011-05-29 | Shinya Aoki | WIN | Rich Clementi | |
| 2011-09-24 | Shinya Aoki | WIN | Rob McCullough | |
| 2011-12-31 | Shinya Aoki | WIN | Satoru Kitaoka | |
| 2012-04-21 | Eddie Alvarez | WIN | Shinya Aoki | |
| 2012-10-12 | Eddie Alvarez | WIN | Patricky Freire | |
| 2013-11-02 | Eddie Alvarez | WIN | Michael Chandler | |
| 2014-09-27 | Donald Cerrone | WIN | Eddie Alvarez | |
| 2015-01-03 | Donald Cerrone | WIN | Myles Jury | |
| 2015-01-18 | Donald Cerrone | WIN | Ben Henderson | |
| 2015-05-23 | Donald Cerrone | WIN | John Makdessi | |
| 2015-12-20 | Rafael dos Anjos | WIN | Donald Cerrone | |
| 2016-07-07 | Eddie Alvarez | WIN | Rafael dos Anjos | Eddie Alvarez’s second reign. |
| 2016-11-12 | Conor McGregor | WIN | Eddie Alvarez | |
| 2018-10-06 | Khabib Nurmagomedov | WIN | Conor McGregor | |
| 2019-09-07 | Khabib Nurmagomedov | WIN | Dustin Poirier | |
| 2020-10-25 | Khabib Nurmagomedov | WIN | Justin Gaethje | Khabib Nurmagomedov retires |
| 2021-12-11 | Charles Oliveira | WIN | Dustin Poirier | Vacant title, top contenders |
| 2022-05-07 | Charles Oliveira | WIN | Justin Gaethje | |
| 2022-10-22 | Islam Makhachev | WIN | Charles Oliveira | |
| 2023-02-12 | Islam Makhachev | WIN | Alexander Volkanovski | |
| 2023-10-21 | Islam Makhachev | WIN | Alexander Volkanovski | |
| 2024-06-01 | Islam Makhachev | WIN | Dustin Porrier |
I think that Poirier vs McGregor 2 was for the lineal championship. Khabib- unofficially retired – said that they were the best lightweight at the moment. Poirier was a former interim champion and after the loss against Khabib he faced and defeated a top 5 (Hooker). Conor was the former UFC undisputed & Lineal Champion and after the loss agaist Khabib he faced and defeated a top 5 (Cerrone), although in a ww bout. Poirer at the moment of victory against Conor was the uncrowned champion.