Manchester City invited Karius and his family to England after watching him in Germany's under-16 game against Azerbaijan, and completed his signing on 1 July 2009.
Manchester City mengundang Karius dan keluarganya ke Inggris setelah menontonnya di pertandingan U-16 Jerman melawan Azerbaijan, dan menyelesaikan penandatanganan kontraknya pada 1 Juli 2009.