The 31-year-old has joined Phunya Sele Sele on a two-year deal, days after failing to agree terms with Kaizer Chiefs.
Goal reported on Tuesday that Amakhosi will not be signing Mabena, and that Celtic had already made contact with the player over a possible move.
Now, the Free State outfit has announced Mabena as their third major signing this week, having already acquired the services of Lucky Baloyi and Given Mashikinya.
Mabena scored four goals in 31 appearances for Dikwena last season, and despite the Rustenburg-based club's desire to keep him, the player had already made up his mind about seeking greener pastures.
He is expected to lead the Celtic attack that fired blanks for the better of last season.
Celtic could only manage to score 16 goals in 30 league games during the 2016/17 PSL campaign.