Global connectivity, at anyplace and anytime, to provide high-speed, high-quality, and reliable communication channels, is now becoming a reality. The credit mainly goes to the recent technological advances in wireless communications which consist of a wide range of technologies and applications to fulfill the particular needs of end-users in different deployment scenarios (Bluetooth, Wi-Fi, WiMAX, and 3G/4G cellular systems). In such a heterogeneous wireless environment, one of the key ingredients to provide efficient ubiquitous computing, is the design of intelligent handoff algorithms, which select the optimal target network. This paper presents a novel approach for the design and implementation of a multi-criteria vertical handoff decision algorithm for heterogeneous wireless networks to achieve seamless mobility while maximizing end-users' satisfaction. After weighting the network parameters, a ranking algorithm based on the fuzzy extension of the the Techniques for Order Preference by Similarity to Ideal Solution (TOPSIS) is used to prioritize all the available networks within the coverage of the mobile user. Simulation results are provided and compared with a benchmark for a single user scenario.