In the recent work, the hairy Vaidya black hole solution has been obtained by using the gravitational decoupling method. We derive a hairy black hole solution if we assume the existence of a new matter field which can be associated with dark matter. If we consider the gravitational collapse of the matter cloud, described by the new solution, then the result might be a regular (non-singular) black hole. We introduce the regularity conditions and find out how dark matter affects the formation of a regular black hole.