[3] On 20 July 2020, the final day of the regular season, Deportivo de La Coruña's match against Fuenlabrada was suspended indefinitely due to several Fuenlabrada players testing positive for COVID-19, therefore, delaying the official end of the season, whilst relegating Deportivo without even playing their match.
[5] A total of 22 teams contested the league, including fifteen sides from the 2018–19 season, three relegated from the 2018–19 La Liga, and four promoted from the 2018–19 Segunda División B.
On 20 May 2019, Osasuna were the first team to be promoted to La Liga, ending a two-year run in Segunda División, following Granada's 1−0 win against Albacete.
Their relegation was ensured on 5 May 2019, after Real Valladolid beat Athletic Bilbao 1−0, suffering an immediate return to the Segunda Division.
[11] The first team to be relegated from Segunda División were Reus, expelled on 18 January 2019, due to their failure to pay their players.
[14] The fourth and final relegated team was Rayo Majadahonda in a 3–4 away loss at Oviedo with a last-minute goal on 4 June 2019.
[15] The first two teams to achieve promotion were Racing Santander and Fuenlabrada on 2 June 2019 after defeating Atlético Baleares and Recreativo on aggregate in the play-off semi-finals respectively.