We propose a simple and effective method to selectively excite the fundamental mode of a multimode fiber by adiabatically tapering a fusion splice to a single-mode fiber. We experimentally demonstrate the method by adiabatically tapering splice (taper $\text{waist}=15\mu \mathrm{m}$ , uniform $\text{length}=40\mathrm{mm}$ ) between single-mode and multimode fiber and show that it provides a successful mode conversion/connection and allows for almost perfect fundamental mode excitation in the multimode fiber. Excellent beam quality $(M^2\sim 1.08)$ was achieved with low loss and high environmental stability.