| Res. | Record | Opponent | Method | Event | Date | Round | Time | Location | Notes |
| Win | 20–10 (1) | Dustin Stoltzfus | Decision (unanimous) | UFC Fight Night: Lopes vs. Silva | September 13, 2025 | 3 | 5:00 | San Antonio, Texas, United States | Catchweight (191 lb) bout; Gastelum missed weight. |
| Loss | 19–10 (1) | Joe Pyfer | Decision (unanimous) | UFC 316 | June 7, 2025 | 3 | 5:00 | Newark, New Jersey, United States | |
| Win | 19–9 (1) | Daniel Rodriguez | Decision (unanimous) | UFC on ABC: Whittaker vs. Aliskerov | June 22, 2024 | 3 | 5:00 | Riyadh, Saudi Arabia | Return to Middleweight. |
| Loss | 18–9 (1) | Sean Brady | Submission (kimura) | UFC on ESPN: Dariush vs. Tsarukyan | December 2, 2023 | 3 | 1:43 | Austin, Texas, United States | Welterweight bout. |
| Win | 18–8 (1) | Chris Curtis | Decision (unanimous) | UFC 287 | April 8, 2023 | 3 | 5:00 | Miami, Florida, United States | Fight of the Night. |
| Loss | 17–8 (1) | Jared Cannonier | Decision (unanimous) | UFC on ESPN: Cannonier vs. Gastelum | August 21, 2021 | 5 | 5:00 | Las Vegas, Nevada, United States | |
| Loss | 17–7 (1) | Robert Whittaker | Decision (unanimous) | UFC on ESPN: Whittaker vs. Gastelum | April 17, 2021 | 5 | 5:00 | Las Vegas, Nevada, United States | Fight of the Night. |
| Win | 17–6 (1) | Ian Heinisch | Decision (unanimous) | UFC 258 | February 13, 2021 | 3 | 5:00 | Las Vegas, Nevada, United States | |
| Loss | 16–6 (1) | Jack Hermansson | Submission (heel hook) | UFC Fight Night: Figueiredo vs. Benavidez 2 | July 19, 2020 | 1 | 1:18 | Abu Dhabi, United Arab Emirates | |
| Loss | 16–5 (1) | Darren Till | Decision (split) | UFC 244 | November 2, 2019 | 3 | 5:00 | New York City, New York, United States | |
| Loss | 16–4 (1) | Israel Adesanya | Decision (unanimous) | UFC 236 | April 13, 2019 | 5 | 5:00 | Atlanta, Georgia, United States | For the interim UFC Middleweight Championship. Fight of the Night. |
| Win | 16–3 (1) | Ronaldo Souza | Decision (split) | UFC 224 | May 12, 2018 | 3 | 5:00 | Rio de Janeiro, Brazil | Fight of the Night. |
| Win | 15–3 (1) | Michael Bisping | KO (punch) | UFC Fight Night: Bisping vs. Gastelum | November 25, 2017 | 1 | 2:30 | Shanghai, China | Performance of the Night. |
| Loss | 14–3 (1) | Chris Weidman | Submission (arm-triangle choke) | UFC on Fox: Weidman vs. Gastelum | July 22, 2017 | 3 | 3:45 | Uniondale, New York, United States | |
| NC | 14–2 (1) | Vitor Belfort | NC (overturned) | UFC Fight Night: Belfort vs. Gastelum | March 11, 2017 | 1 | 3:52 | Fortaleza, Brazil | Originally a TKO (punches) win for Gastelum; overturned after he tested positive for a marijuana metabolite. |
| Win | 14–2 | Tim Kennedy | TKO (punches) | UFC 206 | December 10, 2016 | 3 | 2:45 | Toronto, Ontario, Canada | Return to Middleweight. |
| Win | 13–2 | Johny Hendricks | Decision (unanimous) | UFC 200 | July 9, 2016 | 3 | 5:00 | Las Vegas, Nevada, United States | Catchweight (171.25 lb) bout; Hendricks missed weight. |
| Loss | 12–2 | Neil Magny | Decision (split) | The Ultimate Fighter Latin America 2 Finale: Magny vs. Gastelum | November 21, 2015 | 5 | 5:00 | Monterrey, Mexico | Fight of the Night. |
| Win | 12–1 | Nate Marquardt | TKO (corner stoppage) | UFC 188 | June 13, 2015 | 2 | 5:00 | Mexico City, Mexico | Middleweight bout. |
| Loss | 11–1 | Tyron Woodley | Decision (split) | UFC 183 | January 31, 2015 | 3 | 5:00 | Las Vegas, Nevada, United States | Catchweight (180 lb) bout; Gastelum missed weight. |
| Win | 11–0 | Jake Ellenberger | Submission (rear-naked choke) | UFC 180 | November 15, 2014 | 1 | 4:46 | Mexico City, Mexico | Performance of the Night. |
| Win | 10–0 | Nico Musoke | Decision (unanimous) | UFC Fight Night: Swanson vs. Stephens | June 28, 2014 | 3 | 5:00 | San Antonio, Texas, United States | Catchweight (172.75 lb) bout; Gastelum missed weight. |
| Win | 9–0 | Rick Story | Decision (split) | UFC 171 | March 15, 2014 | 3 | 5:00 | Dallas, Texas, United States | |
| Win | 8–0 | Brian Melancon | Submission (rear-naked choke) | UFC Fight Night: Condit vs. Kampmann 2 | August 28, 2013 | 1 | 2:26 | Indianapolis, Indiana, United States | Welterweight debut. |
| Win | 7–0 | Uriah Hall | Decision (split) | The Ultimate Fighter: Team Jones vs. Team Sonnen Finale | April 13, 2013 | 3 | 5:00 | Las Vegas, Nevada, United States | Won The Ultimate Fighter 17 Middleweight Tournament. |
| Win | 6–0 | Mike Ashford | TKO (punches) | Rage in the Cage 161 | July 20, 2012 | 1 | 1:57 | Chandler, Arizona, United States | |
| Win | 5–0 | Bill Smallwood | Submission (rear-naked choke) | RUF MMA: Cage Rage on the River 2 | July 7, 2012 | 1 | 0:56 | Parker, Arizona, United States | |
| Win | 4–0 | Mike Gentile | TKO (punches) | Desert Rage Full Contact Fighting 10 | October 22, 2011 | 2 | 2:32 | Yuma, Arizona, United States | |
| Win | 3–0 | Yair Moguel | Submission (kimura) | Latin American Warriors 1 | July 16, 2011 | 3 | 2:26 | Mexicali, Mexico | |
| Win | 2–0 | Jose Sanchez | TKO (submission to punches) | Latin American Fighter 1 | December 11, 2010 | 2 | 1:38 | Mexicali, Mexico | |
| Win | 1–0 | Luis Magana | Submission (armbar) | Warrior CF 1 | March 28, 2009 | 1 | N/A | Mexicali, Mexico | Middleweight debut. |