Gamma-ray binaries are systems composed of a massive O or Be-type star and a compact object that show a non-thermal energy distribution that peaks in the MeV-GeV band. Currently, only 9 of such systems are known, and those containing O-type stars are runaways. Because some properties of these systems are not fully understood, the discovery of new gamma-ray binaries may help to answer many open questions, and eventually may open new ones. To discover new gamma-ray binaries we search for runaway stars within catalogs of massive stars using Gaia astrometric data. We present here the current status of our project with tens of new runaway O and Be stars identified,
together with preliminary multi-wavelength information. We will also provide an outlook of the future steps to enlarge the population of gamma-ray binaries.