Kaeser qualified for the men's 200 m breaststroke at the 2012 Summer Olympics in London, by breaking a long-course Swiss record and eclipsing a FINA B-cut of 2:12.09 from the European Championships in Debrecen, Hungary. He challenged seven other swimmers on the fourth heat, including top medal favorites Clark Burckle of the United States and Ryo Tateishi of Japan. Kaeser rounded out the field to last place by more than a second behind Hungary's Ákos Molnár in 2:13.49. Kaeser failed to advance into the semifinals, as he placed twenty-fourth overall in the preliminary heats.