The Colombian international, 27, spent the second half of the 2013-14 campaign on loan at West Ham United.
"I'll be joining a great team," Armero told Milan's official television channel. "I want to find my place here and do well."
Following their eighth-place finish in the Serie A table last season, Milan have signed 14 new players ahead of the new campaign.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Atalanta BCAtalanta | 13 | 9 | 1 | 3 | 34 | 16 | 18 | 28 |
| 2 | Inter Milan | 13 | 8 | 4 | 1 | 31 | 14 | 17 | 28 |
| 3 | Napoli | 12 | 8 | 2 | 2 | 19 | 9 | 10 | 26 |
| 4 | Fiorentina | 12 | 7 | 4 | 1 | 25 | 10 | 15 | 25 |
| 5 | Juventus | 13 | 6 | 7 | 0 | 21 | 7 | 14 | 25 |
| 6 | Lazio | 12 | 8 | 1 | 3 | 25 | 14 | 11 | 25 |
| 7 | AC Milan | 12 | 5 | 4 | 3 | 20 | 14 | 6 | 19 |
| 8 | Bologna | 11 | 4 | 6 | 1 | 15 | 13 | 2 | 18 |
| 9 | Udinese | 12 | 5 | 1 | 6 | 15 | 18 | -3 | 16 |
| 10 | Empoli | 12 | 3 | 6 | 3 | 9 | 10 | -1 | 15 |
| 11 | Torino | 12 | 4 | 2 | 6 | 15 | 18 | -3 | 14 |
| 12 | Roma | 12 | 3 | 4 | 5 | 14 | 17 | -3 | 13 |
| 13 | Parma | 13 | 2 | 6 | 5 | 17 | 21 | -4 | 12 |
| 14 | Hellas VeronaHellas Verona | 13 | 4 | 0 | 9 | 17 | 32 | -15 | 12 |
| 15 | CagliariCagliari | 13 | 2 | 5 | 6 | 14 | 24 | -10 | 11 |
| 16 | Genoa | 13 | 2 | 5 | 6 | 11 | 24 | -13 | 11 |
| 17 | Como | 12 | 2 | 4 | 6 | 13 | 23 | -10 | 10 |
| 18 | Lecce | 12 | 2 | 3 | 7 | 5 | 21 | -16 | 9 |
| 19 | Monza | 12 | 1 | 5 | 6 | 10 | 15 | -5 | 8 |
| 20 | VeneziaVenezia | 12 | 2 | 2 | 8 | 11 | 21 | -10 | 8 |
| > Serie A Full Table | |||||||||
