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 | Udinese | 4 | 3 | 1 | 0 | 7 | 4 | 3 | 10 |
| 2 | Napoli | 4 | 3 | 0 | 1 | 9 | 4 | 5 | 9 |
| 3 | Inter Milan | 4 | 2 | 2 | 0 | 9 | 3 | 6 | 8 |
| 4 | Juventus | 4 | 2 | 2 | 0 | 6 | 0 | 6 | 8 |
| 5 | Torino | 4 | 2 | 2 | 0 | 5 | 3 | 2 | 8 |
| 6 | Lazio | 4 | 2 | 1 | 1 | 8 | 6 | 2 | 7 |
| 7 | Hellas VeronaHellas Verona | 4 | 2 | 0 | 2 | 6 | 5 | 1 | 6 |
| 8 | Empoli | 4 | 1 | 3 | 0 | 3 | 2 | 1 | 6 |
| 9 | Atalanta BCAtalanta | 4 | 2 | 0 | 2 | 8 | 8 | 0 | 6 |
| 10 | AC Milan | 4 | 1 | 2 | 1 | 9 | 6 | 3 | 5 |
| 11 | Genoa | 4 | 1 | 2 | 1 | 4 | 5 | -1 | 5 |
| 12 | Parma | 4 | 1 | 1 | 2 | 6 | 7 | -1 | 4 |
| 13 | Lecce | 4 | 1 | 1 | 2 | 1 | 6 | -5 | 4 |
| 14 | Fiorentina | 4 | 0 | 3 | 1 | 5 | 6 | -1 | 3 |
| 15 | Monza | 4 | 0 | 3 | 1 | 3 | 4 | -1 | 3 |
| 16 | Roma | 4 | 0 | 3 | 1 | 2 | 3 | -1 | 3 |
| 17 | Bologna | 4 | 0 | 3 | 1 | 4 | 7 | -3 | 3 |
| 18 | Como | 4 | 0 | 2 | 2 | 3 | 7 | -4 | 2 |
| 19 | CagliariCagliari | 4 | 0 | 2 | 2 | 1 | 6 | -5 | 2 |
| 20 | VeneziaVenezia | 4 | 0 | 1 | 3 | 1 | 8 | -7 | 1 |
| > Serie A Full Table | |||||||||
