The 32-year-old has joined on a free transfer until the end of the season from League One rivals Tranmere Rovers.
Dadi is much-travelled having had spells in Austria and France before a move to Aberdeen in August 2001. He scored 5 times in 21 starts for the Pittodrie club before a switch to Livingston.
There, Dadi scored 4 times in 19 starts. He left for Tranmere in August 2003 and had a very good first season at Prenton Park with 19 goals.
He was used more as a substitute last season and had yet to feature in the current campaign before his switch to the City Ground.