The past six UFC championship fights have ended in a knockout or submission.
Pettis, Mendes, Hyun Gyu Lim and Pascal Krauss earned $50,000 post-fight bonuses.
UFC 164 drew an announced attendance of 9,178 for a live gate of $907,116.
Betting favorites went 8-4 on the card.
Total fight time for the 12-bout card was 2:56:23.
Pettis' submission of Henderson marked just the third time in history a UFC lightweight title fight has ended with a submission.
Pettis earned just the eighth armbar victory in a UFC championship fight.
Henderson was defeated by submission for the first time since March 31, 2007 – a span of 2,346 days (6.5 years) and 19 fights. The former champion had defended 32 of 32 submission attempts in his UFC/WEC career prior to UFC 164.
Barnett earned his first UFC victory since March 22, 2002 – a span of 4,180 days (11.5 years) and 25 fights. Barnett's 4,180-day gap between UFC wins is the second largest margin in history behind Mark Coleman (4,537 days).
Mir has been knocked out in seven of his eight professional defeats.
Mir is on the first three-fight losing streak of his 24-fight career.
Mendes (15-1 MMA, 6-1 UFC) is the first fighter in featherweight history to win four straight fights by knockout.
Mendes' nine career UFC/WEC featherweight victories are second to champ Jose Aldo for the most all-time.
Mendes' four-fight knockout streak is the longest streak of finishes in his 16-bout professional career.
Guida suffered his first loss since dropping to the UFC featherweight division and fell to 1-3 in his past four fights overall.
Guida was knocked out for the first time in his 44-fight career.
Brandon Vera (12-7 MMA, 8-7 UFC) fell to 1-4 (with one no-contest) in his past six fights. Vera's record when competing in the UFC heavyweight division dropped to 4-3.
Dustin Poirier (14-3 MMA, 6-2 UFC) and Mendes became the second and third featherweight fighters to earn six UFC victories.
Gleison Tibau (28-9 MMA, 13-7 UFC) has never been taken down more than once in a single bout throughout his 20-fight UFC career.
Tim Elliott (10-3-1 MMA, 2-1 UFC) outlanded Louis Gaudinot (6-3 MMA, 1-2 UFC), 270 to 41, in total strikes. The +229 total strike differential is the fourth largest margin ever in a UFC fight and second largest margin ever in a three-round bout. Chael Sonnen owns the record with a +256 differential against Anderson Silva at UFC 117.
Elliott's 270 total strikes landed are the fourth-most ever in a single UFC fight.
Pascal Krauss (11-2 MMA, 2-2 UFC) and Nikita Krylov (15-3 MMA, 0-1 UFC) were knocked out for the first time in their professional careers.
Hyun Gyu Lim (12-3-1 MMA, 2-0 UFC) is just the second fighter in UFC history (Thiago Alves) to earn two consecutive knockout victories stemming from knee strikes.
Ryan Couture (6-3 MMA, 0-2 UFC) is 1 for 13 on takedown attempts in his two-fight UFC career. He went 0-6 against Al Iaquinta (6-2-1 MMA, 1-1 UFC).
Magnus Cedenblad (11-4 MMA, 1-1 UFC) scored the fifth fastest submission in UFC middleweight history by tapping out Jared Hamman (13-6 MMA, 2-5 UFC) with a guillotine choke at 0:57 of Round 1.