Yes. The radius of the "event horizon," which is the spherical boundary that serves as the point of no return, grows as it swallows more mass. For a Schwarzschild black hole (which doesn't rotate and has no charge), the event horizon radius is 2GM/(c^2), where c is the speed of light, M is the mass of the black hole, and G is the gravitational constant.

The singularity at the center doesn't grow. But a black hole's "size" generally refers to the radius of its event horizon.

Wolfram Alpha computes it for you: http://www.wolframalpha.com/input/?i=schwarzschild+radius+fo...