Mthembu's initial contract with the Bethlehem-based outfit expired on June 30, even though the forward still continued training with the Nedbank Cup champions.
Eymael had been assessing Matlakala, while fellow striker Eleazar Rodgers recently joined Stars after a two-year spell with Bidvest Wits.
"Mthembu has signed yes, for one year," an excited Eymael tells snl24.com/kickoff.
"It's good having him back, he was always there for me, he never left. So for me it's a good thing ja.
"Now we have three strikers, Matlakala, him and Rodgers.