The 2021–22 season marked Rayo Vallecano's 98th year in existence and, most notably, their first season back in Spain's top flight, La Liga, following promotion. Competing in both La Liga and the Copa del Rey, the club's league fixtures were officially announced on 30 June 2021, setting the stage for their return to elite Spanish football. The first-team squad was finalized as of 2 February 2022, with the roster supplemented by reserve team players and several individuals out on loan. The campaign involved a series of player transfers (both in and out) and pre-season friendlies designed to strengthen the squad for the challenges ahead. While specific match results are not detailed in the summary, the club's primary objectives were to secure their top-flight status and make a competitive run in the domestic cup competition. Ultimately, this season represented a fresh and significant chapter for the Madrid-based club as they re-established themselves among Spain's footballing elite.