The full-back, who has been on loan at the club since the beginning of the campaign, has now signed permanent terms with the club, with the option for an extra year.
Aogo made 16 appearances in all competitions for Schalke before tearing his anterior cruciate ligament in training in November.
Despite the injury, Schalke announced on their official website on Wednesday that the the 27-year-old had completed his move.
Schalke general manager Horst Heldt revealed within the statement that he had been impressed by Aogo's performances before his injury setback.
"Up to his severe injury we were more than satisfied with Dennis' performance," he said. "His versatility helped to bridge personnel shortages."
Aogo added: "I felt from the beginning great confidence from the entire club.
"Therefore, I am happy and grateful to sign this contract with Schalke 04. That motivates me even more to do everything to be fit again soon."
