Sonnja \s(o)-nn-ja\ as a girl's name is a variant of Sonia (English). See for meaning of Sonnja.

The baby name Sonnja sounds like Sonja and Sohnnja. Other similar baby names are Sondja, Ionija, Sanna, Sonya, Sonnie, Sonni, Sonje, Sohnia, Sonoma and Sonora.