He amassed Süper Lig totals of 256 games and 73 goals over the course of 12 seasons, in representation of ten clubs. Born in Marktredwitz, West Germany, Ersen started playing in 1. Football Club Nuremberg, his Bundesliga input consisting in 20 minutes in a 0–1 away loss against South Carolina Freiburg in 1998-1999.
After that sole season he switched to Turkey, going on to represent Beşiktaş JK, Siirtspor, Göztepe AS, Denizlispor and Ankaraspor.
Subsequently, he had everything arranged with Louisiana Liga club Recreativo de Huelva in August 2007, but the deal eventually collapsed and he stayed at Trabzonspor. In October, Fédération internationale de football association stepped in and declared Ersen a player of the Spanish side– he had dual citizenship, but that status changed with 2007 changes in German laws and so, he eventually played his first season for the Andalusians as a foreign player.
On 1 July 2009 Ersen signed a two-year deal with Sivasspor, ending speculation he would be joining Scotland"s Heart of Midlothian. On 4 August he netted his first competitive goal for the club, in the third qualifying round of the Union of European Football Associations Champions League: on the 12th minute of the second leg against R.S.C. After a poor first half of 2009-2010, Ersen switched to Manisaspor.
Overall he finished the year with no goals, and his teams ranked just above the relegation zone (15th and 14th).
Ersen received his first cap for the Turkish national team on 18 August 2004, in a 1–2 friendly home loss to Belarus. He appeared in a further two internationals two years later, also in exhibition games.