Bulgaria First League

The first football championship in Bulgaria was held in 1924 as a knockout tournament. It was organised by the Bulgarian National Sports Federation (BNSF). The six inaugural teams were Vladislav Varna, Orel Vratsa, Levski Sofia, Krakra Pernik, Pobeda Plovdiv and Chernomorets Burgas, each having won and representing its regional sports federation, called sportna federatsiya. The championship was abandoned, because of a dispute between Vladislav and Levski over the replay of the final game. In the following 1925 season, SK Vladislav became the first champion of Bulgaria. The championship was reorganised for three seasons, from season 1937–38 to 1939–40, ten teams participated in a round-robin tournament, called the National Football Division.

The inaugural season of the A Republican Football Group began in the autumn of 1948. The ten teams participating in the league were Levski, Septemvri, Lokomotiv, Slavia and Spartak from the capital city Sofia, and Botev Varna, Botev Burgas, Slavia Plovdiv, Marek Stanke Dimitrov, Benkovski in a spring-autumn cycle like in the Soviet Union. In the autumn of 1949, qualification tournaments were played to determine the teams that would play in the next 1950 season. In the next two seasons the number of teams in the league was increased to 12, and for the 1953 season there were 15 teams (the 16th team was the Bulgaria national team). In seasons 1954 and 1955 there were 14 teams in the league, and in seasons 1956 and 1957 there were 10.^[]

In 1958, the championship was again stopped after the spring half-season, as had happened in 1948. New re-organizations were accepted and the league was again going to be played in the autumn-spring format. Despite the fact that the teams had played just 1 match, CDNA was crowned as the champion of Bulgaria.^[]

The frequent changes in the number of teams in A Group continued in the 1960s. In the first two seasons after the reforms in 1958, the number of teams in the league was 12, in the period 1960–1962 – 14, until season 1967/68, when the teams were 16.

There were new reforms at the end of the 1960s. There were many mergers between Bulgarian clubs. The most-famous are between CSKA Red Flag and Septemvri Sofia in CSKA September Flag, the capital teams Levski and Spartak in Levski-Spartak, Lokomotiv and Slavia in Slavia, the Plovdiv teams Botev, Spartak and Academic in Trakiya. Mergers happened between other Bulgarian clubs too. These mergers between clubs and reforms in A Group were made at the winter break of the 1968/69 season.

After the winter reforms in 1968 until 2000, A Group remained with 16 teams, except in seasons 1971/72 and 1972/73, when 18 teams competed in the league.

The Bulgarian Football Union decided to make reforms. The Premier Professional Football League, created in the autumn of 2000, had 14 teams participating in it. At the end of the 2000/01 season, the last two teams were directly relegated to the lower division and the team that finished 12th had the chance to compete in the promotion/relegation play-off for the remaining place in the league. Levski Sofia became champions in the first season of the Premier League.

In the 2001/02 season there was experimentation with the regulations. The championship was divided into two phases. In the first phase the teams played a regular season, each team playing twice against all the others, once home and once away. The second phase was a play-off phase.

In the following season, 2002/03, the championship returned to the regulations of 2000/01 – 14 teams playing in a home and away format. For the first time in 6 years, CSKA Sofia became champions.

The Bulgarian A Professional Football Group was created in 2003. The group was formed by 16 teams, each playing twice against all the others, once home and once away. In the first season of the newly created A Group, the 2003–04 season, for the first time in history, Lokomotiv Plovdiv became champions, finishing with 75 points. In 2004–05, CSKA Sofia won A Group for the 30th time. For the next two seasons, Levski Sofia were champions under manager Stanimir Stoilov. From 2005–06 the league's name has been A Football Group. In 2007–08, CSKA became champions of A Group for a record-breaking 31st time without a loss out of 30 matches. But in the summer, UEFA didn't give a licence for the club to play in the UEFA Champions League qualifying rounds and Levski Sofia entered to play in the tournament instead of CSKA. In the following season Levski Sofia won their last A Group title, finishing one point ahead of CSKA. Later on, two consecutive seasons Litex Lovech won another two titles like in 1997–98 and 1998–99. In 2011–12, after winning promotion from B Group, Ludogorets Razgrad became the second team after Litex to win the A Group in their first season.

The Bulgarian Football Union made some changes in the format of A Group prior to season 2013–14 with the reduction of the number of the teams participating in the top league from 16 to 14 and the reintroduction of the two phase league with a regular season and a playoff/play out phase. For the 2014–15 season, the league was once more decreased, this time to 12 teams, keeping the two phase format. This season was memorable since two of the most popular and successful clubs, CSKA Sofia and Lokomotiv Sofia, were both excluded from the league, despite finishing in the top 5 places. Both teams had accumulated debts and did not have the financial resources to pay them, so the BFU decided to take away their professional licenses. This was the first time in the history of the A Group that CSKA was relegated.^[] For the 2015–16 season, the BFU decided to further decrease the number of teams competing, this time to just 10, with a quadruple round robin format introduced, a format used in the Croatian First Football League and Albanian Kategoria Superiore.

On 7 June 2016 the league's name was changed to First Professional Football League, following approval of new licensing criteria for the clubs. The new league name also came with a new format change, the fourth such in the last four seasons. A total of 14 teams would compete, and the season would consist of two phases, a regular season phase, where each team plays each other team twice, followed by a playoff phase, where the top six teams from the regular season compete for the title as well as European competition spots, while the remaining eight teams would compete for avoiding relegation to the Second League. This format was used from 2016 up until 2021.

In 2021, the BFU decided to once more change the format of the league. This time, the league would still consist of a regular season stage where teams compete against each other twice, but then the league would split into three phases. The top six clubs would again compete for the title and European spots, while teams ranked 7-10 at the end of the regular season would play in the Europa Conference Group, with the 7th placed team competing against the 4th placed team from the Championship group for a UEFA Europa Conference League spot. The bottom four teams would compete to avoid relegation. This format lasted only one season, however, as the league was expanded to 16 teams for the 2022–23 season. The three phases were kept identical though, with the exception being that six teams would compete in the relegation group instead of four. For the 2024–25 season, the format was modified yet again. After the regular season concludes, the league would split into a top four group to determine the champion and European competition places, a second group for teams ranked fifth through eight to determine the team that would compete in the playoffs for UEFA Conference League (team that finished fourth in the top group would play against the fifth-placed team), as well as a bottom eight group consisting of teams competing to avoid relegation, with the last two teams being directly relegated, while the 14th and 15th placed teams would compete in a playoff against the third and fourth placed teams from the Second League.