The 26-year-old striker scored 25 goals in 91 appearances during three seasons in France.
Park says ''it is a dream to be here and I am really proud to be an Arsenal player. Now I just want to show how good I am and prove myself.''
Arsenal says the deal is subject to the completion of the registration processes and he will have J. Y. Park on the back of his No. 9 shirt as he prefers to be known as ''Ju.''
Werder Bremen defender Per Mertesacker and Fenerbahce left back Andre Santos has also been linked with moves to Arsenal.
Arsene Wenger's side has collected just one point from its first three league matches and was routed 8-2 by Manchester United on Sunday.