The 2012Kansas City Chiefsseason was the franchise's 43rd season in the National Football league, the 53rd overall and the first full season under head coach Romeo Crennel, who served as the interim head coach for the final three games of the 2011 season following Todd Haley's termination. The Chiefs failed to rebound from their 7–9 record in 2011, and were eliminated from playoff contention in Week 12. Although sharing the same 2–14 record as the Jacksonville Jaguars for the worst record of the season, the Chiefs were statistically the worst team overall, and thereby "earned" the right to the first pick in the 2013 NFL Draft.
Kansas City suffered from quarterback controversy all season and tied with the Arizona Cardinals for most interceptions (20) with Matt Cassel throwing 12 and his late season replacement Brady Quinn throwing 8. The Chiefs had the worst record in the NFL in offensive passing.
The Chiefs also lost 17 fumbles giving them 37 giveaways – tied for worst in the NFL with the New York Jets and Philadelphia and tying with Philadelphia for the NFL's worst giveaway/takeaway differential with −24.
Season low points included:
Starting the season tying the 1929 record of Buffalo Bisons for most games without ever leading in regulation time (8 games). The Chiefs had rallied in week 3 against the New Orleans Saints to tie the game in regulation and then won in overtime 27–24 but had never led until the overtime final. The Chiefs broke the streak in Week 10 against the Pittsburgh Steelers when they led 10–0 in the second quarter before losing the game 16–13 in overtime. The Chiefs had had a bye in Week 7.
In Week 4 the Chiefs had six turnovers in a loss to San Diego.
Fans formed the "Save Our Chiefs" organization. They wore black to games to protest and hired an airplane to fly over Arrowhead Stadium on game days towing a banner that read, "Restore Hope: Fire Pioli."
When asked why running back Jamaal Charles carried the ball only 5 times in a week 8 loss to the Oakland Raiders, Romeo Crennel responded "Now, that I'm not exactly sure, either." 
On December 1, 2012, Chiefs linebacker Jovan Belcher murdered his girlfriend at their home and then drove to the Arrowhead Stadium practice field where he shot himself in the head in front of general manager Scott Pioli and Coach Crennel.
In Week 15 the Chiefs didn't have a first down until the third quarter in a loss against Oakland.
In Week 16 the team rushed for a franchise record of 352 yards against the Colts and still lost the game.
In Week 17 the Chiefs matched the 1981 Baltimore Colts season record of losing 9 games by 14 points or more in one season as the Chiefs lost to Denver.
The Chiefs won the home game 27–21 against the Carolina Panthers the day after the Belcher suicide at the stadium complex in Week 13. The victory snapped the Chiefs 8-game losing streak.
Jamaal Charles rushing was the main bright spot of the team. Charles tied a NFL record for players with single play rushes of 80 yards or more (3) held by Chris Johnson and Barry Sanders. Charles ran for touchdowns of 91 yards in Week 3 against the Saints, 80 yards on the first play of the game in Week 14 against Cleveland and 84 yards on the first play of the second half in Week 16 against Indianapolis. He also tied Larry Johnson for franchise record of two 200+ yard games in one season with his games versus the Saints and Colts. Charles in the Colts game officially broke Jim Brown's NFL record for yards per carry when he averaged 5.82 yards on 770 attempts through the Colts game (compared with Brown's 5.22 yards on 2,359 attempts). To qualify for the career record a player had to have 750 attempts. Charles ended the season as the NFL's 4th leading rusher (behind Adrian Peterson of Minnesota, Alfred Morris of the Washington Redskins and Marshawn Lynch of Seattle. Minnesota, Washington and Seattle went to the NFL playoffs. Charles ranked 28th in the season in rushing touchdowns (5). The Chiefs as a team ranked 5th in rushing.
Against the Atlanta Falcons, the Kansas City Chiefs were behind early in the first quarter when Falcons quarterback Matt Ryan threw an 8-yard touchdown pass to wide receiver Julio Jones to lead 7–0. The Chiefs answered with a 39-yard field goal from Ryan Succop to make it 7–3. The Falcons scored on their next drive with a 34-yard field goal from Matt Bryant to extend their lead 10–3. In the second quarter, Matt Cassel threw a 22-yard touchdown pass to tight end Kevin Boss to tie the game at 10–10. Matt Ryan and the Falcons took the lead again with a 14-yard touchdown pass to wide receiver Julio Jones to go up 17–10. Matt Cassel scored on a 5-yard rushing touchdown on the Chiefs next possession to make the score tied again at 17–17. The Falcons just managed to extend their lead before halftime with a 21-yard field goal by Matt Bryant to lead 20–17 coming into the half.
In the third quarter, Matt Ryan scored on a 5-yard touchdown run to make it 27–17. Shortly afterward, Matt Ryan tossed a 7-yard touchdown pass to tight end Tony Gonzalez to further extend their lead 34–17. In the fourth quarter, the Atlanta falcons scored twice on field goals of 30 and 41 yards by Matt Bryant to lead 40–17. Late in the fourth quarter, the Chiefs scored on a 4-yard run by running back Shaun Draughn. The final score of this game is 24–40 as the Kansas City Chiefs fall to 0–1
In the first quarter, the Buffalo Bills scored first with a 17-yard rushing touchdown by running back C.J. Spiller to lead 7–0. In the second quarter, the Bills scored again with a 5-yard rushing touchdown by C.J. Spiller to lead 14–0. The Bills continued to extend their lead when quarterback Ryan Fitzpatrick threw a 10-yard touchdown pass to tight end Scott Chandler to lead 21–0 at halftime.
In the third quarter, the Chiefs finally scored with a 33-yard field goal by Ryan Succop to make it 3–21. The Bills answered with a 49-yard touchdown pass from quarterback Ryan Fitzpatrick to wide receiver Steve Johnson to make the score 28–3. The Bills continued to dominate with an 88-yard punt return touchdown by Leodis McKelvin to lead 35–3. In the fourth quarter, the Chiefs finally got going with Matt Cassel throwing a 33-yard touchdown pass to wide receiver Dwayne Bowe to make the score 10–35. The Chiefs managed to score again with Matt Cassel throwing a 5-yard touchdown pass to wide receiver Dwayne Bowe. The Chiefs fantastic effort in the fourth quarter was not enough, the final score is 17–35 as the Chiefs fall to 0–2.
With the loss, the Chiefs fell to 1–7 and were swept by the Chargers for the first time since 2009. Kansas City now holds the NFL record of not leading at any point during regulation at eight games.
The Chiefs led for the first time all season in this game with a first-quarter touchdown which gave them the lead 7–0. After relinquishing the lead, the Chiefs tied the game at 13–13 at the end of regulation to force overtime. However, despite the fact that they got the ball in overtime, QB Matt Cassel was picked off by Lamarr Woodley and the ball was returned to the Chiefs' 5-Yard line setting up the game winning field goal for the Steelers as the Chiefs lost the game 16–13 and their record dropped to 1–8.
This would be the second time all season that the Chiefs would lead a game as they kicked for the first 3 points off of a 34-yard field goal from Ryan Succop. However, the Bengals' defense shut the Chiefs down as the Chiefs dropped to 1–9 and 0–5 in home games. The Chiefs who had 31 giveaways on the season would eventually end up with only 6 giveaways for the remainder of the season.
Before the game, tragedy struck the Chiefs as linebacker Jovan Belcher committed suicide after the shooting of his girlfriend the day before. Snapping a home losing skid of their own, the Chiefs won at Arrowhead for the first time since they robbed the Green Bay Packers of a perfect regular season during Week 15 of the 2011 season by snapping the latter's 19-game winning streak.
The Chiefs improved to 2–10 with the surprising win.
TV announcers (CBS): Kevin Harlan and Solomon Wilcots
The Chiefs fell to 2–12 after being shutout only for the second time against the Raiders in team history. Because the Raiders (4–10) swept the Chiefs, Kansas City clinched fourth-place in the AFC West for the second straight year.