Watch Queue Queue Currently, Anja Mertens is 32 years old. FACT She is a seasoned equestrian popular on YouTube like Nicole Equestrian . Anja will celebrate her 33rd birthday on a Friday, September 25th. SEE ALSO Anja Mertens’s net worth as of 2020. Discover the most famous people named Anja including Anja Rubik, Anja Mertens, Anja Nissen, Anja Dujakovic, Anja Leuenberger and many more. American Exchange Student Forced to leave Germany due to the Coronavirus This video is unavailable. Watch Queue Queue. Birthday. Her next birthday is away.