Whilst in Paris Viljoen helped the side to win the Top 14 championship making 10 appearances and scoring 2 tries.
The 28 year old will join Aironi after five Super Rugby seasons, all with the Cheetahs.
Viljoen made his debut in 2002 Currie Cup with Leopards before joining Griquas and then Free State Cheetahs. Last season he finished with 8 tries and was Player of the Year for the Bloemfontein side.
"We are pleased to have signed Frans on a two year contract. He will add experience, power and physicality in the back row area, so important in modern rugby," said Director of Rugby Franco Tonni. "If necessary, he can also play as a lock. That's why we think he's the right guy in the right place."
Guinness PRO12 Aironi News
63x46.png){kind=logo}
){kind=link}
){kind=link}
){kind=link}
){kind=link}
){kind=link}
){kind=link}