| 2004 All-Ireland Under-21 Football Championship | |
| Bodyclass: | vevent |
| Headerstyle: | background:#BFD7FF; |
| Labelstyle: | white-space: nowrap |
| Datastyle: | white-space: nowrap |
| Header1: | Championship details |
| Label2: | Dates |
| Label3: | Teams |
| Header4: | All-Ireland Champions |
| Label5: | Winning team |
| Data5: | Armagh (1st win) |
| Label6: | Captain |
| Data6: | Ciaran McKeever |
| Label7: | Manager |
| Data7: | Peter Rafferty |
| Header8: | All-Ireland Finalists |
| Label9: | Losing team |
| Data9: | Mayo |
| Label10: | Captain |
| Label11: | Manager |
| Data11: | John Maughan |
| Header12: | Provincial Champions |
| Label13: | Munster |
| Data13: | Cork |
| Label14: | Leinster |
| Data14: | Kildare |
| Label15: | Ulster |
| Data15: | Armagh |
| Label16: | Connacht |
| Data16: | Mayo |
The 2004 All-Ireland Under-21 Football Championship was the 41st staging of the All-Ireland Under-21 Football Championship since its establishment by the Gaelic Athletic Association in 1964.
Dublin entered the championship as defending champions, however, they were defeated by Kildare in the Leinster final replay.
On 2 October 2004, Armagh won the championship following a 2–8 to 1–9 defeat of Mayo in the All-Ireland final.[1] This was their first All-Ireland title.
Semi-finals
Final