The aim of this study was to evaluate the effects of different methods (traditional, diode laser, Er,Cr:YSSG laser and passive ultrasonic irrigation activation) of post cavity irrigation on the bond strength of fiber posts. Root canal treatments were performed on 135 human mandibular premolars to be used for the push-out test, and then different irrigation activation methods were applied. After the fiber post was cemented with two different resin cements, 1-mm-thick-disc-shaped sections were obtained from the apical, middle, and coronal levels of the posts. Root dentin sections were subjected to the push-out bond strength test at a speed of 0.5 mm/min with a universal testing device. Confocal laser scanning microscopy and SEM analysis were performed. In both resin cements, higher bond strength values were found at the apical level of the fiber posts in the specimens that were activated by diode laser. At the coronal level of the fiber post, the Er,Cr;YSGG laser irradiated specimens showed the highest bond strength values in both resin cement groups. The most common failure in both resin cement groups was cohesive. Irrigation methods, with the exception of conventional irrigation, generally increased the bond strength of the fiber post.