The 2021 NCAA Division I FBS football season was the 152nd season of college football in the United States organized by the National Collegiate Athletic Association (NCAA) at its highest level of competition, the Football Bowl Subdivision. The regular season began on August 28, 2021,^[1] and ended on December 11, 2021. The postseason began on December 17, with the main games ending on January 10, 2022, with the College Football Playoff National Championship at Lucas Oil Stadium in Indianapolis, and the all-star portion of the post-season concluding with the inaugural HBCU Legacy Bowl on February 19, 2022. It was the eighth season of the College Football Playoff (CFP) system.^[2] It was the first time since 2016 that no major team finished the season undefeated as the Cincinnati Bearcats, the season's last undefeated team, were defeated in the 2021 Cotton Bowl Classic.

The following rule changes, recommended by the NCAA Football Rules Committee for the 2021 season on March 12 of that year, were approved by the NCAA Playing Rules Oversight Panel on April 22.^[3][4]

• In overtime, teams scoring a touchdown will be required to attempt a two-point conversion starting with the second overtime period (previously the third overtime period). If the scores are still tied at the expiration of the second overtime, teams will be required to attempt alternating two point conversions starting with the third overtime (previously the fifth overtime period). Teams can still choose to go for the PAT kick or two-point conversion during the first overtime period. The first game using this procedure was on September 18 between Utah and San Diego State, won by SDSU 33–31 in three overtimes. On October 23, the all-time FBS record for most overtimes in a single game was broken when Illinois defeated host Penn State 20–18 in nine overtimes.
• Permanently extending the team area from between the 25-yard lines to between the 20-yard lines. A rule implemented for the 2020 season due to the COVID-19 pandemic had extended this area to between the 15-yard lines, but it had been scheduled to revert to the 25 for 2021.
• Provide a framework to allow a school or conference to request a postgame video review about questionable actions (i.e. feigning injuries to stop the clock and slow down teams' momentum) through the NCAA secretary-rules editor/national coordinator of officials.
• Explicitly prohibiting video board and lighting system operators from creating "any distraction that obstructs play", with violations being deemed unsportsmanlike conduct.
• If replay overturns a call on the field, the game clock will only be adjusted inside of the last 2:00 of the first half and the last 5:00 of the second half.

Another rule change was made during the season:

• After Pitt quarterback Kenny Pickett's fake slide in the 2021 ACC Championship Game against Wake Forest, the NCAA Football Rules Committee changed the interpretation of the "QB Slide Rule" to require officials to interpret a fake slide as "giving himself up" and blow the play dead.

"Points of Emphasis" for the 2021 season included:

• Any taunting action toward an opponent will be penalized.
• Automatic unsportsmanlike conduct penalties will be imposed on a coach who leaves the team area or goes onto the field of play to argue with the officials.
• Officials are to be more alert to players significantly in violation of uniform rules (specifically pants, jerseys, and T-shirts that extend below the torso), and to send violators out of the game to correct the issue.

• On April 15, 2021, the NCAA Division I Council adopted legislation that extended the so-called "one-time transfer exception" to all D-I sports, with the Division I Board of Directors ratifying this on April 28. This allows student-athletes in baseball, men's and women's basketball, football, and men's ice hockey to transfer one time without having to sit out a year, placing them under the same transfer regulations that previously applied to all other D-I sports.^[5][6]
• On June 10, the College Football Playoff announced that it had begun work on a proposal to expand the playoff to 12 teams in the indefinite future. Under the proposed format:^[7]
  • The six conference champions ranked highest by the CFP selection committee would receive automatic berths. The field would be filled out by the committee's six highest-ranked remaining teams, with no restrictions on conference affiliation.
  • The four highest-ranked conference champions would receive first-round byes.
  • The remaining 8 teams would play first-round games hosted by the higher seeds.
  • The quarterfinals and semifinals would be hosted by existing bowl games, with the final continuing to be held at a separately determined neutral site.
• On June 21, the Supreme Court of the United States ruled in National Collegiate Athletic Association v. Alston that the NCAA had no authority to limit education-related non-cash compensation for athletes, but stopped short of addressing direct cash payments to college athletes.
• On July 21, the Houston Chronicle reported that Oklahoma and Texas had approached the Southeastern Conference about the possibility of joining that league, and that an announcement could come in early August. The SEC and both schools refused comment on this report, but did not issue definitive denials.^[8][9]
• On July 26, Oklahoma and Texas notified the Big 12 Conference that the two schools do not wish to extend its grant of television rights beyond the 2024–25 athletic year and intend to leave the conference.^[10][11]
• On July 27, Oklahoma and Texas reached out to the SEC about acceptance into the conference in 2025.^[12][13]
• July 28 – The Big 12 sent a cease-and-desist letter to ESPN, accusing the network of tortious interference by working with other conferences attempting to lure Big 12 members in a bid to ease Oklahoma's and Texas' exits for the SEC. The network denied the allegations.^[14]
• July 29 – The presidents and chancellors of the 14 current SEC members voted unanimously to extend invitations to Oklahoma and Texas, effective in 2025.^[15]
• July 30 – The boards of regents of both Oklahoma and Texas unanimously accepted the SEC's invitations.^[16]
• August 16 – The Associated Press released its preseason rankings, with Alabama as the overwhelming choice for #1. Other ranking highlights:^[17]
  • Iowa State received its highest AP ranking in school history at #7.
  • Coastal Carolina and Louisiana, respectively #22 and #23, became the first Sun Belt Conference teams to be ranked in the preseason.
• August 24 – The Pac-12 Conference, Big Ten Conference, and Atlantic Coast Conference announced an alliance designed to "stabilize the current environment" by collaborating on a number of issues, including scheduling for football, men's and women's basketball.^[18]
• September 3 – Multiple media outlets reported that the Big 12 was on the verge of inviting four schools—American Athletic Conference members Cincinnati, Houston, and UCF, plus BYU, an FBS independent and otherwise a member of the non-football West Coast Conference. All four schools were reportedly preparing membership applications, and reports were that their future entrance could be approved as early as the next scheduled meeting of Big 12 presidents on September 10. The entry timeline was uncertain at the time of the report, but 2024 was seen as the likeliest date.^[19][20]
• September 10 – BYU, Cincinnati, Houston, and UCF were officially announced as incoming Big 12 members no later than 2024–25.^[21]
• October 18 – Yahoo Sports reported that The American, which had been rocked by the impending departure of three of its most prominent schools, was preparing to receive applications from six of the 14 members of Conference USA—Charlotte, Florida Atlantic, North Texas, Rice, UAB, and UTSA. Should all six schools join, The American would become a 14-team conference in all sports. (Navy is a football-only member, while Wichita State is a full member but does not sponsor football.)^[22]
• October 19 – ESPN reported that all six C-USA members named in Yahoo Sports' report had submitted applications to The American, and that each would receive a formal letter by the end of that week (October 22) detailing the terms of expansion.^[23]
• October 21 – The six aforementioned C-USA members were announced as incoming members of The American at a date to be determined.^[24]
• October 22 – The Action Network reported that C-USA member Southern Miss had accepted an invitation to join the Sun Belt Conference in 2023, though no formal announcement had then been made. The report added that the Sun Belt was preparing to add two other C-USA members, Marshall and Old Dominion, as well as FCS program James Madison. At the time, formal announcements of new members were expected on October 25, but an announcement regarding Marshall was likely to wait until after the school announced its new president on October 28.^[25]
• October 26 – Southern Miss was officially announced as a Sun Belt member, effective no later than July 2023.^[26] In other Sun Belt realignment news, it was reported that Old Dominion's arrival would be announced later that week, and that James Madison's board had scheduled an emergency meeting on October 29 (presumably to discuss a Sun Belt invitation).^[27]
• October 27 – Old Dominion was officially announced as a Sun Belt member, also effective no later than July 2023. This marked ODU's return to that conference after an absence of more than 30 years.^[28]
• October 30 – The day after both the Sun Belt Conference and Marshall issued tweets indicating that the Thundering Herd had accepted a Sun Belt invitation,^[29] this move was officially announced.^[30]
• November 5 – Multiple media outlets reported that Conference USA, which had nine of their schools depart to other separate conferences, handed out invitations to four schools: FBS independents Liberty and New Mexico State as well as FCS programs Jacksonville State and Sam Houston State, which were all accepted.^[31]
• November 6 – James Madison made their move to the Sun Belt official, effective no later than July 2023.^[32]
• November 23 – Cincinnati became the first Group of Five team ever to receive a top-four College Football Playoff ranking, coming in at fourth in this week's rankings.^[33]
• December 5 – The College Football Playoff field was revealed, featuring (in order of seeding) Alabama, Michigan, Georgia, and Cincinnati. This marked the first time a Group of Five team received a CFP berth.^[34]
• December 17 – After Coastal Carolina's 47–41 win over Northern Illinois in the Cure Bowl, Coastal quarterback Grayson McCall finished the season with a 207.6 passer rating, breaking the FBS record of 203.1 set last season by Alabama's Mac Jones.^[35]
• December 18 – During Western Kentucky's 59–38 win over Appalachian State in the Boca Raton Bowl, WKU quarterback Bailey Zappe broke two major single-season FBS passing records and equaled a single-season FBS total offense record:
  • 5,967 passing yards (surpassing the 5,833 yards of Texas Tech's B. J. Symons in 2003)^[36]
  • 62 passing touchdowns (surpassing the 60 TDs of LSU's Joe Burrow in 2019)^[36]
  • 65 touchdowns responsible for (combined passing and rushing; equals Burrow's 2019 mark)^[37]
• December 22 – After San Diego State's 38–24 win over UTSA in the Frisco Bowl, SDSU punter and placekicker Matt Araiza ended the season with a 51.19-yard punting average, breaking the FBS single-season record of 50.98 yards set by Braden Mann of Texas A&M in 2018.^[38]
• January 1 - Ohio State receiver Jaxon Smith-Njigba set an all-time FBS bowl game record with 347 receiving yards on 15 catches in the Rose Bowl game against Utah. He also broke the Ohio State team record for receiving yards in a game and in a single season.^[39]

• This was the first season for UAB at Protective Stadium, replacing its old stadium, Legion Field. The first game was a 36–12 UAB loss to Liberty on October 2.^[40]
• With the closure of Aloha Stadium to future events and plans to build a new stadium on the site, Hawaii is playing through at least the 2023 season at the on-campus Clarence T. C. Ching Athletics Complex, home to the university's track and field program. A project expanded the stadium to at least 10,000 in time for the 2021 season, and was completed in just over four months.^[41][42] However, due to city and state COVID-19 public health orders restricting gatherings, and taking into consideration the isolated nature of the state from the mainland in receiving aid to deal with the pandemic, all games were to be played behind closed doors until further notice. It is the only team in Division I FBS that is restricting attendance.^[43] On October 8, 2021, Mayor of Honolulu Rick Blangiardi gave permission for the stadium to host 1,000 spectators. All spectators must wear masks and be fully-vaccinated (if capable of being so).^[44] In November 2021, capacity limitations were lifted, but all other restrictions remained in force.^[45]
• This was the last of two seasons that San Diego State spent at its temporary home of Dignity Health Sports Park in Carson, California. SDSU will move to the new Snapdragon Stadium, nearing completion on part of the property formerly occupied by the team's since-demolished San Diego Stadium, next season.

Rankings reflect the AP Poll entering each week.

Rankings reflect the AP Poll. Rankings for Week 10 and beyond will list College Football Playoff Rankings first and AP Poll second. Teams that failed to be a top 10 team for one poll or the other will be noted.

• Week 1
  • No. 5 Georgia defeated No. 3 Clemson, 10–3 (Bank of America Stadium, Charlotte, North Carolina)
• Week 2
  • No. 10 Iowa defeated No. 9 Iowa State, 27–17 (Jack Trice Stadium, Ames, Iowa)
• Week 5
  • No. 2 Georgia defeated No. 8 Arkansas, 37–0 (Sanford Stadium, Athens, Georgia)
  • No. 7 Cincinnati defeated No. 9 Notre Dame, 24–13 (Notre Dame Stadium, South Bend, Indiana)
• Week 6
  • No. 3 Iowa defeated No. 4 Penn State, 23–20 (Kinnick Stadium, Iowa City, Iowa)
• Week 9
  • No. 8 Michigan State defeated No. 6 Michigan, 37–33 (Spartan Stadium, East Lansing, Michigan)
• Week 12
  • No. 4/5 Ohio State defeated No. 7/7 Michigan State, 56–7 (Ohio Stadium, Columbus, Ohio)
• Week 13
  • No. 5/6 Michigan defeated No. 2/2 Ohio State, 42–27 (Michigan Stadium, Ann Arbor, Michigan)
  • No. 7/7 Oklahoma State defeated No. 10/10 Oklahoma, 37–33 (Boone Pickens Stadium, Stillwater, Oklahoma)
• Week 14
  • No. 3/4 Alabama defeated No 1/1 Georgia 41–24 (2021 SEC Championship Game, Mercedes-Benz Stadium, Atlanta, Georgia)
  • No. 9/9 Baylor defeated No. 5/5 Oklahoma State, 21–16 (2021 Big 12 Championship Game, AT&T Stadium, Arlington, Texas)

This section lists instances of unranked teams defeating AP Poll-ranked teams during the season.

The top 25 from the AP and USA Today Coaches Polls.

Rankings in this section are based on CFP rankings released prior to the games.

There are 42 team-competitive FBS post-season bowl games, with two teams advancing to a 43rd – the CFP National Championship game. Normally, a team is required to have a .500 minimum winning percentage during the regular season to become bowl-eligible (six wins for an 11- or 12-game schedule, and seven wins for a 13-game schedule). If there are not enough winning teams to fulfill all open bowl slots, teams with losing records may be chosen to fill all 84 bowl slots. Additionally, on the rare occasion in which a conference champion does not meet eligibility requirements, they are usually still chosen for bowl games via tie-ins for their conference.