Rafał Antoniewski was one of the top Polish junior. Twice took 4th place at the European Youth Chess Championship: 1994 (U14) and 1995 (U16). In 1996 was 12th in the World Junior Chess Championship (U16) in Minorca.
In 2014 was second in the Polish Blitz Chess Championship in Bydgoszcz.
Rafał Antoniewski has also competed successfully in several Polish Team Chess Championships (team silver in 2002, 2010).