The 2021 Joint EuCNC & 6G Summit, initiated this year, builds on putting together two successful conferences in the area of telecommunications: EuCNC, in its 30th edition of a series, supported by the European Commission; the 6G Summit, in its 3rd edition, originated from the 6G Flagship programme in Finland, one of the very first in its area. The conference is sponsored by the IEEE Communications Society and by the European Association for Signal Processing, and focuses on all aspects of telecommunications ranging from 5G deployment and mobile IoT to 6G exploration and future communications systems and networks, including experimentation and testbeds, and applications and services. It brings together cutting-edge research and world-renown industries and businesses, globally attracting in the last years more than 1 300 delegates from more than 40 countries all over the world, to present and discuss the latest results, and an exhibition space of more than 1 500 m2 with more than 70 exhibitors, for demonstrating the technology developed in the area, namely within research projects from EU R&I programmes.