Vagnozzi made his ATP Tour singles debut at the 2004 Grand Prix Hassan II on clay courts in Casablanca, Morocco when he successfully advanced through three qualifying rounds to reach his first career main draw.

In qualifying he defeated Talal Ouahabi, followed by leading Thomas Shimada 6–0, 2–0 when he had to retire from the match, and finally Björn Rehnquist to gain a main draw birth.

He made his ATP Tour doubles debut at the 2005 Croatia Open where he received a direct entry alongside Slovenian player Ladislav Švarc.

He reached 1 career doubles final on the ATP Tour at the 2010 Swedish Open alongside compatriot Andreas Seppi.

Vagnozzi, alongside Darren Cahill, is currently the coach of fellow Italian ATP player Jannik Sinner.