Dielectric barrier discharge (DBD) plasma was used to change the wettability of a SU-8 photoresist, reducing the contact angle and improving the surface smoothness. As most polymers, SU-8 has hydrophobic surfaces which prevents the adhesion of biological samples when used to fabricate biochemical sensors. Here, DBD Plasma treatment was conducted over the SU-8 surface, reducing the contact angle from 78° to 12°. The advantage of this treatment is that the SU-8 surface maintains the hydrophilic surface behavior over 24 h time period. DBD plasma modified the SU-8 surface wettability under low temperature variation and does not cause great irregularities on the surface. The highest value of root mean square surface roughness after 10 min exposure was 2.9 ± 0.3 nm.