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 | 11 | 8 | 1 | 2 | 18 | 8 | 10 | 25 |
| 2 | Inter Milan | 11 | 7 | 3 | 1 | 25 | 13 | 12 | 24 |
| 3 | Atalanta BCAtalanta | 11 | 7 | 1 | 3 | 29 | 14 | 15 | 22 |
| 4 | Fiorentina | 11 | 6 | 4 | 1 | 22 | 9 | 13 | 22 |
| 5 | Lazio | 11 | 7 | 1 | 3 | 24 | 14 | 10 | 22 |
| 6 | Juventus | 11 | 5 | 6 | 0 | 19 | 7 | 12 | 21 |
| 7 | AC Milan | 10 | 5 | 2 | 3 | 17 | 11 | 6 | 17 |
| 8 | Udinese | 11 | 5 | 1 | 5 | 14 | 16 | -2 | 16 |
| 9 | Bologna | 10 | 3 | 6 | 1 | 12 | 11 | 1 | 15 |
| 10 | Torino | 11 | 4 | 2 | 5 | 15 | 16 | -1 | 14 |
| 11 | Empoli | 11 | 3 | 5 | 3 | 8 | 9 | -1 | 14 |
| 12 | Roma | 11 | 3 | 4 | 4 | 12 | 14 | -2 | 13 |
| 13 | Hellas VeronaHellas Verona | 11 | 4 | 0 | 7 | 16 | 24 | -8 | 12 |
| 14 | CagliariCagliari | 11 | 2 | 3 | 6 | 9 | 19 | -10 | 9 |
| 15 | Genoa | 11 | 2 | 3 | 6 | 8 | 21 | -13 | 9 |
| 16 | Como | 11 | 2 | 3 | 6 | 12 | 22 | -10 | 9 |
| 17 | Parma | 11 | 1 | 6 | 4 | 14 | 17 | -3 | 9 |
| 18 | Monza | 11 | 1 | 5 | 5 | 10 | 14 | -4 | 8 |
| 19 | VeneziaVenezia | 11 | 2 | 2 | 7 | 10 | 19 | -9 | 8 |
| 20 | Lecce | 11 | 2 | 2 | 7 | 4 | 20 | -16 | 8 |
| > Serie A Full Table | |||||||||
