The 28-year-old defender, whose existing contract was due to expire next summer, has penned a new five-year deal at the Stadio Olimpico.
The left-back joined Lazio from Dinamo Bucharest in 2008, and has made over 150 appearances for Stefano Pioli's side.
Radu, a Romanian international with 14 caps for his country, is Lazio's vice-captain, and helped the club to third-place finish in Serie A last season.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Napoli | 13 | 9 | 2 | 2 | 20 | 9 | 11 | 29 |
| 2 | Atalanta BCAtalanta | 13 | 9 | 1 | 3 | 34 | 16 | 18 | 28 |
| 3 | Inter Milan | 13 | 8 | 4 | 1 | 31 | 14 | 17 | 28 |
| 4 | Fiorentina | 13 | 8 | 4 | 1 | 27 | 10 | 17 | 28 |
| 5 | Lazio | 13 | 9 | 1 | 3 | 28 | 14 | 14 | 28 |
| 6 | Juventus | 13 | 6 | 7 | 0 | 21 | 7 | 14 | 25 |
| 7 | AC Milan | 12 | 5 | 4 | 3 | 20 | 14 | 6 | 19 |
| 8 | Bologna | 12 | 4 | 6 | 2 | 15 | 16 | -1 | 18 |
| 9 | Udinese | 13 | 5 | 2 | 6 | 16 | 19 | -3 | 17 |
| 10 | Empoli | 13 | 3 | 7 | 3 | 10 | 11 | -1 | 16 |
| 11 | Torino | 13 | 4 | 3 | 6 | 16 | 19 | -3 | 15 |
| 12 | Roma | 13 | 3 | 4 | 6 | 14 | 18 | -4 | 13 |
| 13 | Parma | 13 | 2 | 6 | 5 | 17 | 21 | -4 | 12 |
| 14 | Hellas VeronaHellas Verona | 13 | 4 | 0 | 9 | 17 | 32 | -15 | 12 |
| 15 | Lecce | 13 | 3 | 3 | 7 | 6 | 21 | -15 | 12 |
| 16 | CagliariCagliari | 13 | 2 | 5 | 6 | 14 | 24 | -10 | 11 |
| 17 | Genoa | 13 | 2 | 5 | 6 | 11 | 24 | -13 | 11 |
| 18 | Como | 13 | 2 | 4 | 7 | 13 | 25 | -12 | 10 |
| 19 | Monza | 13 | 1 | 6 | 6 | 11 | 16 | -5 | 9 |
| 20 | VeneziaVenezia | 13 | 2 | 2 | 9 | 11 | 22 | -11 | 8 |
| > Serie A Full Table | |||||||||
