| 2019-05-11 | UFC 237: Namajunas vs. Andrade | Lightweight | Clay Guida def. B.J. Penn | Decision (unanimous) (29–28, 29–28, 29–27) | 3 | 5:00 |
| 2018-12-29 | UFC 232: Jones vs. Gustafsson 2 | Lightweight | Ryan Hall def. B.J. Penn | Submission (heel hook) | 1 | 2:46 |
| 2017-06-25 | UFC Fight Night: Chiesa vs. Lee | Featherweight | Dennis Siver def. B.J. Penn | Decision (majority) (28–28, 29–28, 29–27) | 3 | 5:00 |
| 2017-01-15 | UFC Fight Night: Rodríguez vs. Penn | Featherweight | Yair Rodríguez def. B.J. Penn | TKO (front kick and punches) | 2 | 0:24 |
| 2014-07-06 | The Ultimate Fighter: Team Edgar vs. Team Penn Finale | Featherweight | Frankie Edgar def. B.J. Penn | TKO (punches) | 3 | 4:16 |
| 2012-12-08 | UFC on Fox: Henderson vs. Diaz | Welterweight | Rory MacDonald def. B.J. Penn | Decision (unanimous) (30–26, 30–26, 30–27) | 3 | 5:00 |
| 2011-10-29 | UFC 137: Penn vs. Diaz | Welterweight | Nick Diaz def. B.J. Penn | Decision (unanimous) (29–28, 29–27, 29–28) | 3 | 5:00 |
| 2011-02-27 | UFC 127: Penn vs. Fitch | Welterweight | B.J. Penn vs. Jon Fitch | Draw (majority) (28–29, 28–28, 28–28) | 3 | 5:00 |
| 2010-11-20 | UFC 123: Rampage vs. Machida | Welterweight | B.J. Penn def. Matt Hughes | KO (punches) | 1 | 0:21 |
| 2010-08-28 | UFC 118: Edgar vs. Penn 2 | Lightweight | Frankie Edgar def. B.J. Penn title | Decision (unanimous) (50–45, 50–45, 50–45) | 5 | 5:00 |
| 2010-04-10 | UFC 112: Invincible | Lightweight | Frankie Edgar def. B.J. Penn title | Decision (unanimous) (50–45, 48–47, 49–46) | 5 | 5:00 |
| 2009-12-12 | UFC 107: Penn vs. Sanchez | Lightweight | B.J. Penn def. Diego Sanchez title | TKO (doctor stoppage) | 5 | 2:37 |
| 2009-08-08 | UFC 101: Declaration | Lightweight | B.J. Penn def. Kenny Florian title | Submission (rear-naked choke) | 4 | 3:54 |
| 2009-01-31 | UFC 94: St-Pierre vs. Penn 2 | Welterweight | Georges St-Pierre def. B.J. Penn title | TKO (corner stoppage) | 4 | 5:00 |
| 2008-05-24 | UFC 84: Ill Will | Lightweight | B.J. Penn def. Sean Sherk title | TKO (flying knee and punches) | 3 | 5:00 |
| 2008-01-19 | UFC 80: Rapid Fire | Lightweight | B.J. Penn def. Joe Stevenson title | Submission (rear-naked choke) | 2 | 4:02 |
| 2007-06-23 | The Ultimate Fighter: Team Pulver vs. Team Penn Finale | Lightweight | B.J. Penn def. Jens Pulver | Submission (rear-naked choke) | 2 | 3:12 |
| 2006-09-23 | UFC 63: Hughes vs. Penn | Welterweight | Matt Hughes def. B.J. Penn title | TKO (punches) | 3 | 3:53 |
| 2006-03-04 | UFC 58: USA vs. Canada | Welterweight | Georges St-Pierre def. B.J. Penn | Decision (split) (29–28, 28–29, 29–28) | 3 | 5:00 |
| 2004-01-31 | UFC 46: Supernatural | Welterweight | B.J. Penn def. Matt Hughes title | Submission (rear-naked choke) | 1 | 4:39 |
| 2003-02-28 | UFC 41: Onslaught | Lightweight | B.J. Penn vs. Caol Uno title | Draw (split) (48–46, 47–48, 48–48) | 5 | 5:00 |
| 2002-09-27 | UFC 39: The Warriors Return | Lightweight | B.J. Penn def. Matt Serra | Decision (unanimous) (29–28, 29–28, 29–28) | 3 | 5:00 |
| 2002-05-10 | UFC 37: High Impact | Lightweight | B.J. Penn def. Paul Creighton | TKO (punches) | 2 | 3:23 |
| 2002-01-11 | UFC 35: Throwdown | Lightweight | Jens Pulver def. B.J. Penn title | Decision (majority) (48–45, 47–47, 48–47) | 5 | 5:00 |
| 2001-11-02 | UFC 34: High Voltage | Lightweight | B.J. Penn def. Caol Uno | KO (punches) | 1 | 0:11 |
| 2001-06-29 | UFC 32: Showdown in the Meadowlands | Lightweight | B.J. Penn def. Din Thomas | TKO (knee) | 1 | 2:42 |
| 2001-05-04 | UFC 31: Locked and Loaded | Lightweight | B.J. Penn def. Joey Gilbert | TKO (punches) | 1 | 4:57 |