The Peter Schiergen-trained 3-year-old colt ran far out on the course for jockey Andrasch Starke, seizing the lead a half-mile out and finishing well as a 13-2 shot in the 16-horse field.
A thunderstorm shook the race course during the post parade. After the start of the 1 1/2-mile event over a course rated good, Kamsin was racing with the leaders before going for an early move. He overtook Ostland, who finished second. Top Lock ran third.
Kamsin was a beaten favorite in his last start, a Derby trial at Munich.
“I didn't want to make it but the early pace was slow so I took the initiative," said Starke, who won the German Derby for the fifth time. "I was able to set a steady pace and control the race throughout.
"I knew his last form was all wrong. He has been working much better since.”
Franz-Gunther von Gaertner owns Kamsin, a German-bred son of Samum.