We report on the realization of an integrated lasing device consisting of a microsphere optical resonator fused to a tapered optical fiber. A microsphere fabricated from Er:Yb-codoped phosphate glass is heated above its glass transition temperature of 375°C by pumping it at 977 nm with 70 mW via a tapered optical fiber. The onset of thermal stress in the glass at a maximum pumping power results in the sphere melting and fusing to the taper coupler, without inhibition of whispering gallery mode lasing. A taper-fused microsphere laser with ~4.5 µW of lasing power at 1593 nm is demonstrated.