Mark John Byrnes (born 8 February 1982) is an Australian footballer who plays for APIA Leichhardt Tigers in the New South Wales Premier League.

After a short stint with SV Salzburg in Austria, he won two NSL championship medals in a row with Perth Glory.

Due to the demise of the National Soccer League after the 2003/2004 season, in July of that year he signed with Finnish club, FC Hämeenlinna.

[1] He returned to Australia to form part of Melbourne Victory's A-League 2005–06 squad,[2] but found his chances limited by the emergence of younger defenders Adrian Leijer and Daniel Piorkowski.

[7] In 2008, Byrnes went on trial with English lower league football clubs Port Vale and Luton Town.