This is the third meeting of the project MeV2TeV: Particle Physics at Colliders and Astroparticle Observatories, funded by the Spanish Ministry of Science and Innovation under contracts PID2019-107844GB-C21/C22. The project involves researchers from the Universities of Huelva, Pablo de Olavide of Seville, Cordoba and Granada. The aim of the workshop is to discuss ongoing work and explore further possibilities of collaboration among the members of the different research teams.