Cognitive Radio Networks (CRN) focus to enable Secondary Users (SU) to use unutilized Primary User's (PU) spectrum bands and thereby resolve spectrum scarcity. Spectrum sensing and spectrum handoff are critical operations of CRN. Energy detection is a less complex and feasible spectrum sensing method. However, its performance needs to be boosted in low Signal to Noise Ratio (SNR) regions. In case of spectrum handoff, the CRN will have to choose the optimal network from the environment to continue transmission. Maintaining the Quality of Service (QoS) during and after the handoff is a challenging task. To jointly resolve these issues, we have proposed an adaptive threshold based energy detection scheme for spectrum sensing and the application of Multiple Attribute Decision Making (MADM) methods for spectrum handoff. The numerical results show that the proposed adaptive threshold method provides nearly 4 times better performance than the conventional fixed threshold method at low SNR regions. In addition, the proposed MADM methods are found to be efficient for choosing the best network for spectrum handoff. This paper illustrates that the proposed spectrum sensing and handoff schemes jointly increase the performance of the CRN. © 2019 IEEE.