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 | Napoli | 12 | 8 | 2 | 2 | 19 | 9 | 10 | 26 |
| 2 | Atalanta BCAtalanta | 12 | 8 | 1 | 3 | 31 | 15 | 16 | 25 |
| 3 | Fiorentina | 12 | 7 | 4 | 1 | 25 | 10 | 15 | 25 |
| 4 | Inter Milan | 12 | 7 | 4 | 1 | 26 | 14 | 12 | 25 |
| 5 | Lazio | 12 | 8 | 1 | 3 | 25 | 14 | 11 | 25 |
| 6 | Juventus | 12 | 6 | 6 | 0 | 21 | 7 | 14 | 24 |
| 7 | AC Milan | 11 | 5 | 3 | 3 | 20 | 14 | 6 | 18 |
| 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 | 12 | 2 | 6 | 4 | 16 | 18 | -2 | 12 |
| 14 | Hellas VeronaHellas Verona | 12 | 4 | 0 | 8 | 17 | 27 | -10 | 12 |
| 15 | Como | 12 | 2 | 4 | 6 | 13 | 23 | -10 | 10 |
| 16 | CagliariCagliari | 12 | 2 | 4 | 6 | 12 | 22 | -10 | 10 |
| 17 | Genoa | 12 | 2 | 4 | 6 | 9 | 22 | -13 | 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 | |||||||||
