Kasey Bos joins Excelsior Rotterdam on loan

“For Kasey, it’s important that he gets regular game time at the highest possible level”

Bos in action for the U23s. The Australian made 14 appearances for Mainz’s second team in the Regionalliga Südwest last season.

Kasey Bos will join Excelsior Rotterdam on loan for the coming season. The 22-year-old Australian, who spent a long spell on the sidelines last term with a shoulder injury, will now gain more experience with the Eredivisie club. Bos joined Mainz 05 in summer 2025.

“For Kasey, it’s important that he gets regular game time at the highest possible level. Excelsior Rotterdam will give him the chance to continue his development in a strong league, and they are the ideal club for that. Being close to his brother Jordan, who is already playing such an outstanding role at Feyenoord, should also help him settle into a new city,” commented Mainz 05 sporting director Niko Bungert.

First team Six 05ers heading to the World Cup Alle News First team 05ers head to Brandenburg in the DFB-Pokal