Stoica was born in Romania, but left at 13 years old to Italy, in 1989. He joined Pavia Rugby, and switched to Milan in 1996, and after only six appearances in the Serie A league, he was called up for national representation. He made his debut for Italy at the age of 20, against Ireland at Lansdowne Road in Dublin. After spending two seasons with Milan, Stoica left the club and signed with RC Narbonne, who play in the French league.
In 1999, Stoica was included in the Italian squad for the World Cup in Wales. He has also been playing in the Six Nations Championship since Italy were admitted in 2000. After a short stay in England (2000–2001), where he played for Gloucester RFC, Stoica signed with Castres Olympique, and, in 2003, moved on to Montpellier RC. In the same year, he earnt his second World Cup selection with Italy in Australia.
In 2004, Cristian Stoica won the European Shield with current club Montpellier.