An analytical and numerical study of diffusion growth of overcritical gas bubbles at degassing of the supersaturated-by-gas solution with the explicit full-scale influence of viscous forces on internal pressure in the bubbles has been presented. At degassing of supersaturated-by-gas solution, we need to describe not only the dependence of the gas bubble growth rate on the bubble radius and gas supersaturation, but also control how the capillary and viscous effects change the concentration profile of the dissolved gas in supersaturated liquid solution around the growing bubble. Using the approach, presented earlier, we have found how the growth rate of overcritical bubbles depends on gas supersaturation, its diffusivity and solubility in solution, solution viscosity, and surface tension at bubble surface.