In this paper, we obtained the closed form analytical expression for the average detection probability of the energy detector in terms of series form expression over λ-μ fading distribution. We start with the no-diversity case, then further results are extended to two diversity reception cases such as square-law-selection (SLS) and collaborative detection case. Since arriving analytical expression is used for the obtaining the different fading distributions of λ-μ fading channel. The performance analysis of energy detection is also discussed with the receiver operating characteristics (ROC) curves. Our closed form expression is validated by numerical results. © 2016 IEEE.