The 25-year-old's previous deal with the Blues had been due to expire in 2017.
However, the defender, who scored the only goal of the game in Empoli's 1-0 win over Lazio at the weekend, has now agreed a two-year extension.
Former Italy Under-21 international Tonelli has risen through the ranks at the Stadio Carlo Castellani, having made his debut in 2010.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Inter Milan | 32 | 26 | 5 | 1 | 77 | 17 | 60 | 83 |
| 2 | AC Milan | 32 | 21 | 6 | 5 | 63 | 37 | 26 | 69 |
| 3 | Juventus | 33 | 18 | 10 | 5 | 47 | 26 | 21 | 64 |
| 4 | Bologna | 32 | 16 | 11 | 5 | 45 | 25 | 20 | 59 |
| 5 | Roma | 31 | 16 | 7 | 8 | 56 | 35 | 21 | 55 |
| 6 | Lazio | 33 | 16 | 4 | 13 | 42 | 35 | 7 | 52 |
| 7 | Atalanta BCAtalanta | 31 | 15 | 6 | 10 | 57 | 36 | 21 | 51 |
| 8 | Napoli | 32 | 13 | 10 | 9 | 50 | 40 | 10 | 49 |
| 9 | Torino | 32 | 11 | 12 | 9 | 31 | 29 | 2 | 45 |
| 10 | Fiorentina | 31 | 12 | 8 | 11 | 43 | 36 | 7 | 44 |
| 11 | Monza | 32 | 11 | 10 | 11 | 34 | 41 | -7 | 43 |
| 12 | Genoa | 33 | 9 | 12 | 12 | 35 | 40 | -5 | 39 |
| 13 | CagliariCagliari | 33 | 7 | 11 | 15 | 36 | 56 | -20 | 32 |
| 14 | Lecce | 32 | 7 | 11 | 14 | 27 | 48 | -21 | 32 |
| 15 | Hellas VeronaHellas Verona | 32 | 6 | 10 | 16 | 30 | 44 | -14 | 28 |
| 16 | Udinese | 31 | 4 | 16 | 11 | 30 | 47 | -17 | 28 |
| 17 | Empoli | 32 | 7 | 7 | 18 | 25 | 48 | -23 | 28 |
| 18 | FrosinoneFrosinone | 32 | 6 | 9 | 17 | 40 | 63 | -23 | 27 |
| 19 | SassuoloSassuolo | 32 | 6 | 8 | 18 | 39 | 62 | -23 | 26 |
| 20 | Salernitana | 32 | 2 | 9 | 21 | 26 | 68 | -42 | 15 |
| > Serie A Full Table | |||||||||
