The 18-year-old had been linked with a number of clubs after a string of impressive displays for the Australian outfit.
At the age of 15, he became the second-youngster player in history to make his A-League debut.
It is reported that he will cost Roma a transfer fee in the region of €2m (£1.45m).
De Silva made his final appearance for Perth Glory in their 3-1 win over Melbourne City today.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| C | Inter Milan | 37 | 29 | 6 | 2 | 87 | 20 | 67 | 93 |
| 2 | AC Milan | 37 | 22 | 8 | 7 | 73 | 46 | 27 | 74 |
| 3 | Bologna | 37 | 18 | 14 | 5 | 54 | 30 | 24 | 68 |
| 4 | Juventus | 37 | 18 | 14 | 5 | 52 | 31 | 21 | 68 |
| 5 | Atalanta BCAtalanta | 36 | 20 | 6 | 10 | 67 | 39 | 28 | 66 |
| 6 | Roma | 37 | 18 | 9 | 10 | 64 | 44 | 20 | 63 |
| 7 | Lazio | 37 | 18 | 6 | 13 | 48 | 38 | 10 | 60 |
| 8 | Fiorentina | 37 | 16 | 9 | 12 | 58 | 44 | 14 | 57 |
| 9 | Torino | 37 | 13 | 14 | 10 | 36 | 33 | 3 | 53 |
| 10 | Napoli | 37 | 13 | 13 | 11 | 55 | 48 | 7 | 52 |
| 11 | Genoa | 37 | 11 | 13 | 13 | 43 | 45 | -2 | 46 |
| 12 | Monza | 37 | 11 | 12 | 14 | 39 | 49 | -10 | 45 |
| 13 | Hellas VeronaHellas Verona | 37 | 9 | 10 | 18 | 36 | 49 | -13 | 37 |
| 14 | Lecce | 37 | 8 | 13 | 16 | 32 | 54 | -22 | 37 |
| 15 | CagliariCagliari | 38 | 8 | 12 | 18 | 42 | 68 | -26 | 36 |
| 16 | FrosinoneFrosinone | 37 | 8 | 11 | 18 | 44 | 68 | -24 | 35 |
| 17 | Udinese | 37 | 5 | 19 | 13 | 36 | 53 | -17 | 34 |
| 18 | Empoli | 37 | 8 | 9 | 20 | 27 | 53 | -26 | 33 |
| R | SassuoloSassuolo | 37 | 7 | 8 | 22 | 42 | 74 | -32 | 29 |
| R | Salernitana | 37 | 2 | 10 | 25 | 29 | 78 | -49 | 16 |
| > Serie A Full Table | |||||||||
