In almost every activity in space, a large number of parameters need to be continuously monitored to safely control a mission. If this statement is obvious for astronauts vital parameters, it is even truer for supervising the operating status in spacecrafts, satellites as well as living and working modules. To this end, a huge amount of sensors and devices have to be deployed to dynamically configure the space equipment both autonomously and on ground. In this scenario, the weight and the rigidity of all these devices still represents the major challenge, even if the cost per kg of the payload has been considerably reduced in the last few years. Flexible sensors can provide a valuable solution to this issue, offering ultra-light and wearable devices to be used as standalone system or integrated in large networks. In this work, we review the most significant flexible sensors that can potentially represent a valuable solution for the space environment for monitoring a large variety of functions from the structural integrity of a space module to the control of the fine gesture of astronauts in extravehicular activity.