Malaury Martin has finalised his one-year deal with Middlesbrough following his release by Blackpool.
The 22-year-old French midfielder made his debut in the 3-2 friendly victory over Croatian side NK Varazdin after impressing during a trial on Teesside.
Free agent Martin, a former France Under-21 international, spent last season at Blackpool but was plagued by injuries and did not make a single first-team appearance.
Boro boss Tony Mowbray said: “Malaury can do a bit of everything and will be a useful addition to our midfield.
“He can pass, tackle and defend and he has a great shot on him, so we will try to utilise his talents.”