| Mattia Masi | |
| Fullname: | Mattia Masi |
| Birth Date: | 4 December 1984 |
| Birth Place: | City of San Marino, San Marino |
| Height: | 1.67 m |
| Position: | Midfielder |
| Years1: | 2001–2002 |
| Clubs1: | VF Colligiana |
| Caps1: | 2 |
| Goals1: | 0 |
| Years2: | 2004–2005 |
| Clubs2: | San Marino |
| Years3: | 2005–2006 |
| Clubs3: | VF Colligiana |
| Years4: | 2006–2008 |
| Clubs4: | Virtus Poggibonsi |
| Years5: | 2009–2013 |
| Clubs5: | GS Staggia |
| Nationalyears1: | 2005–2006 |
| Nationalteam1: | San Marino |
| Nationalcaps1: | 4 |
| Nationalgoals1: | 0 |
Mattia Masi (born 4 December 1984) is a Sammarinese former footballer who played as a midfielder. He was capped four times by the San Marino national team.