| Teams for 2021 Firekeepers Casino 400 |
|---|
| Car | Team | Driver | Mfg |
|---|---|---|---|
| 00 | William Woehlemann | Quin Houff |  |
| 1 | Chip Ganassi | Kurt Busch | |
| 2 | Roger Penske | Brad Keselowski |  |
| 3 | Richard Childress | Austin Dillon | |
| 4 | Stewart Haas Racing | Kevin Harvick | |
| 5 | Rick Hendrick | Kyle Larson | |
| 6 | Jack Roush | Ryan Newman | |
| 7 | Spire Motorsports | Josh Berry | |
| 8 | Richard Childress | Tyler Reddick | |
| 9 | Rick Hendrick | Chase Elliott | |
| 10 | Stewart Haas Racing | Aric Almirola | |
| 11 | Joe Gibbs | Denny Hamlin |  |
| 12 | Roger Penske | Ryan Blaney | |
| 14 | Stewart Haas Racing | Chase Briscoe | |
| 15 | Rick Ware | Joey Gase | |
| 17 | Jack Roush | Chris Buescher | |
| 18 | Joe Gibbs | Kyle Busch | |
| 19 | Joe Gibbs | Martin Truex, Jr. | |
| 20 | Joe Gibbs | Christopher Bell | |
| 21 | Wood Brothers Racing | Matt DiBenedetto | |
| 22 | Roger Penske | Joey Logano | |
| 23 | 23XI Racing | Bubba Wallace | |
| 24 | Rick Hendrick | William Byron | |
| 34 | Front Row Motorsports | Michael McDowell | |
| 37 | JTG Daughtery Racing | Ryan Preece | |
| 38 | Front Row Motorsports | Anthony Alfredo | |
| 41 | Stewart Haas Racing | Cole Custer | |
| 42 | Chip Ganassi | Ross Chastain | |
| 43 | Richard Petty Motorsports | Erik Jones | |
| 47 | JTG Daughtery Racing | Ricky Stenhouse, Jr. | |
| 48 | Rick Hendrick | Alex Bowman | |
| 51 | Rick Ware | Cody Ware | |
| 52 | Rick Ware | Josh Bilicki | |
| 53 | Rick Ware | Garrett Smithley | |
| 77 | Spire Motorsports | Justin Haley | |
| 78 | BJ McLeod | B.J. McLeod | |
| 99 | Trackhouse Racing | Daniel Suarez | |
