We report herein the discovery of methylamine (CH3NH2) induced defect‐healing (MIDH) of CH3NH3PbI3 perovskite thin films based on their ultrafast (seconds), reversible chemical reaction with CH3NH2 gas at room temperature. The key to this healing behavior is the formation and spreading of an intermediate CH3NH3PbI3⋅xCH3NH2 liquid phase during this unusual perovskite–gas interaction. We demonstrate the versatility and scalability of the MIDH process, and show dramatic enhancement in the performance of perovskite solar cells (PSCs) with MIDH. This study represents a new direction in the formation of defect‐free films of hybrid perovskites. A perovskite smoothie: Treating CH3NH3PbI3 (MAPbI3) perovskite thin films with methylamine gas induces a rapid collapse of the perovskite structure and formation of a liquid phase. Removing the gas causes conversion back into the perovskite structure giving a smooth defect‐free film. Using the film in perovskite solar cells enhances their performance.