Onsen-Yesilyurt is one of the localities of Kahramanmaras Merkez; it had 1,438 registered voters at the 2011 parliamentary election.
AK Parti took 76.7% in the neighborhood at that election. Across Kahramanmaras Merkez the same party stood at 80.3%, putting the neighborhood 3.5 points below the district average. At the 2010 referendum 85.3% of the neighborhood voted 'yes'; across the district that was 89.4%.
Turnout at the 2009 local election was 96.5%, 7.8 points above the district average.