Hinkel, who will make his debut against Stirling in the Scottish Cup on Saturday, told the Sunday Mail: "The next few months are vital because I want to make the Euro 2008 squad.
"This season was bad for me at Sevilla. I need to play and believe that's possible in Scotland.
"I'll fight for my place from the moment I get there."
Dortmund were also interested in Hinkel but the 25-year-old was made to feel more wanted by the Hoops.
He said: "The Celtic directors influenced my decision. They fought for me and it was important to know they had confidence in my ability.
"It will be a challenge. Celtic have a history as one of the best clubs in Europe and Glasgow also has a great football tradition."