The title race had gone to the final day, but Atletico ultimately finished two points clear of second-placed Real Madrid, while Barcelona and Sevilla claimed third and fourth respectively.
Real Sociedad, Real Betis and Europa League finalists Villarreal made up the top seven, while Huesca, Real Valladolid and Eibar were relegated and will therefore play Segunda Division football next term.
It was another fascinating campaign in Spain's top flight with plenty of twists and turns despite the absence of the supporters.
Here, Sports Mole takes on the difficult task of choosing the best La Liga XI from the 2020-21 campaign, and it would be fair to say that there are plenty of familiar names in the lineup.
Goalkeeper: Jan Oblak
In truth, this was not a difficult decision, with Jan Oblak once again the standout goalkeeper in Spain's top flight. The 28-year-old played every minute of his side's title-winning season, conceding just 25 goals in the process, with Atletico once again finishing with the best defensive record in the division.
Oblak, somewhat surprisingly, actually made more saves - 103 - than any other goalkeeper in La Liga during the 2020-21 campaign, while he also produced 18 clean sheets. There have been suggestions that the Slovenia international could move on this summer, which would be a huge problem for Atletico.
Honourable mentions: Thibaut Courtois (Real Madrid), Yassine Bounou (Sevilla), Alex Remiro (Real Sociedad), Edgar Badia (Elche)
Right-back: Kieran Trippier
Kieran Trippier missed a chunk of matches earlier this year due to his FA suspension, but he still played a key role in Atletico's title triumph, making 28 La Liga appearances, providing six assists in the process.
There is no question that the England international has improved defensively under Simeone, and he was a key contributor for the Red and Whites upon his return to the team at the start of March.
Honourable mentions: Jesus Navas (Sevilla)
Centre-backs: Stefan Savic, Jules Kounde
Stefan Savic was a towering presence at the heart of Atletico's defence during the 2020-21 campaign, scoring once in 33 La Liga appearances. The 30-year-old was actually suspended for his side's final game of the season against Valladolid but still played a leading role in their success.
Totalling almost 3,000 minutes of La Liga football this season, Savic had an impressive average pass success rate of 85%, while he won, on average, three aerial battles per match. Atletico's record of 25 goals conceded was the best in the league, and the Montenegro international enjoyed an excellent season.
Alongside Savic is Sevilla's Jules Kounde, who is being linked with some of Europe's biggest clubs, including Manchester United and Real Madrid, due to his form over the last 12 months or so.
The 22-year-old scored twice in 34 La Liga appearances in 2020-21, while he had an average pass success rate of more than 90%, which is staggering for a centre-back, in addition to three aerial battles won per match, so it is not difficult to understand why the Frenchman is so highly rated across the European game.
Honourable mentions: Pau Torres (Villarreal), Mario Hermoso (Atletico), Nacho (Real Madrid)
Left-back: Yannick Carrasco
Yannick Carrasco is not strictly a left-back, but he has largely operated as a left-sided wing-back for Atletico this season, and the 27-year-old has enjoyed an excellent campaign. Boasting six goals and 10 assists in 30 La Liga appearances, the Belgian was a key player for Simeone's side in 2020-21.
There were occasions when he played further forward, but Carrasco's energy and work-rate up and down the left made him a leading figure for Atletico, and it was impossible to leave him out of this team.
Honourable mentions: Jordi Alba (Barcelona), Jose Gaya (Valencia), Javi Galan (Huesca), Marcos Acuna (Sevilla)
Central midfield: Marcos Llorente, Toni Kroos
Marcos Llorente's form during the 2020-21 season was spectacular, and it would be fair to say that the 26-year-old is now one of the most effective players in La Liga. Boasting 12 goals and 11 assists in 37 league appearances, Llorente played a starring role in his side's success.
The Spaniard played as a second striker, a right midfielder and a central midfielder during stages of the season and was a key contributor both going forward and working back. There simply could not have been a Team of the Season without the 26-year-old, who has developed into a wonderful footballer at this level.
Real Madrid's season might have ultimately ended in disappointment, but Toni Kroos's presence in this side cannot be disputed. The 31-year-old was disappointingly forced to miss the end of the campaign due to coronavirus, but a record of three goals and 10 assists in 28 outings is an indication of his form.
The Germany international had a pass success rate of almost 94% across 28 matches, which is a staggering statistic, while he was often the player driving the team forward, particularly during their struggles.
Honourable mentions: Frenkie de Jong (Barcelona), Casemiro (Real Madrid), Mikel Merino (Real Sociedad), Denis Suarez (Celta Vigo), Dani Parejo (Villarreal), Koke (Atletico), Renato Tapia (Celta Vigo), Sergio Canales (Real Betis)
Right wing: Gerard Moreno
Gerard Moreno's numbers in 2020-21 were simply brilliant, scoring 23 times and boasting seven assists in 33 La Liga appearances. Only Lionel Messi (30) found the back of the net on more occasions, and Moreno's consistency was excellent, particularly in the second half of the campaign.
It would be fair to say that the 29-year-old largely plays through the middle for Villarreal, but he has also operated as a right winger this season, and the Spaniard has been placed in that area of the field as it was impossible to leave certain other players out of the side in the final third.
Honourable mentions: Iago Aspas (Celta Vigo), Jorge de Frutos (Levante)
Left wing: Lionel Messi
There was simply not a scenario where Lionel Messi was ever going to be left out of this side; there might have been a host of speculation surrounding the 33-year-old's future, but he still enjoyed an excellent season, scoring 30 times and providing 11 assists in 35 La Liga appearances.
Barcelona ultimately fell short in terms of the title, ending the season down in third position, but Messi finished as the leading scorer in Spain's top flight and was particularly excellent in the second half of the campaign.
Ronald Koeman's side are desperately battling to sign the South American to a new contract, and it will be fascinating to see how the situation develops in the coming weeks.
Honourable mentions: Jose Luis Morales (Levante), Mikel Oyarzabal (Real Sociedad)
Centre-forwards: Luis Suarez, Karim Benzema
Luis Suarez was discarded by Barcelona last summer but their loss was Atletico's gain, as the Uruguay international has played a key role for Simeone's side in 2020-21. The 34-year-old ended the season with 21 goals in 32 La Liga appearances, and he scored the winners in Atletico's last two league matches of the season against Osasuna and Valladolid.
The South American's future at Wanda Metropolitano is unclear, but he will forever be remembered by the club's fans for his contribution this season, and Barcelona will surely be regretting allowing him to leave.
Karim Benzema, meanwhile, enjoyed another excellent season for Real Madrid, finding the back of the net on 23 occasions in 34 appearances, in addition to providing nine assists. Los Blancos have had their problems this season, but the Frenchman was a true leader and once again showed his credentials.
Only Messi scored more La Liga goals than Benzema this term, and Real Madrid would not have been anywhere near the title but for the 33-year-old, who sails into this particular XI alongside Suarez.
Honourable mentions: Alexander Isak (Real Sociedad), Youssef En-Nesyri (Sevilla), Rafa Mir (Huesca), Roger Marti (Levante), Joselu (Alaves), Alvaro Negredo (Cadiz), Santi Mina (Celta Vigo)