Mikić continued to play for Dinamo Zagreb until 2004 and then he left the club after seven seasons for German Bundesliga side 1. FC Kaiserslautern. In his first season in Germany, he made only six Bundesliga appearances for Kaiserslautern and was not a regular in the first part of the 2005–06 season either, making only four appearances in the league, but then he became a regular after the winter break and collected a total of 20 Bundesliga appearances until the end of the season. He did not manage to score any goals in a total of 29 competitive appearances for Kaiserslautern and left the club in June 2006, shortly after they were relegated to the 2. Bundesliga with a 16th-place finish in the first division.