On July 20, 2019, Primera Division awarded a new license to ownership group who wanted a team based in Ahuachapan, This came about after Pasaquina were stripped of their license and were forced to sell their spot, the new team filled the vacancy in the market created by the dissolution of Once Municipal three years earlier. On July 21, 2019, the club announced that Once Deportivo, which had previously been used as a placeholder name for the club, would be the official team name. Once Deportivo announced Uruguayan Pablo Quiñones as its head coach in July 20, 2017, joining general director Roberto Campos in a search for players. Segio Calero was signed as the club's first player on July 22, 2019. Once Deportivo started its inaugural season against Municipal Limeno on 29 July 2019, losing 3–0. The club's first ever goal was a goal scored by Anthony Roque in the Once's third league game, a 2-1 loss against Aguila. Once Deportivo's first win was a 2-1 victory over Isidro Metapan, which came in the fifth round of their first Primera Division season on 18 August 2019. Once Deportivo finished their first season in twelfth position. They failed to make it into the top six teams to reach the finals. Following the conclusion of the season, Once Deportivo sacked Pablo Quinones and hired Spaniard Juan Dieguez to be the new coach. The club bolstered their campaign with the hiring of international players such as Mexicans Marco Granados and Edgar Solis, Nicaraguan Luis Fernando Copete, and Salvaodran such as Marcelo Tejada. The club started the season strongly winning six games, drawing two games and losing three games. On March, 2020 the season was suspended due to coronavirus pandemic. A week later FESFUT the organiser of El Salvador football declared that the final round of matches and the final would be cancelled due to the coronavirus pandemic. The title was subsequently awarded to Once Deportivo, who finished on top of the points table after the eleven rounds that were played. This is Once Deportivo first title in their history. However, at the FESFUT extraordinary meeting on 29 April 2020, it was decided that the Clausura 2020 season title originally awarded to Once Deportivo would be retracted and the title would not be awarded. However, they would remain the third representative of El Salvador in the 2020 CONCACAF League.
Once Deportivo plays its home games at Estadio Simeon Magana in Ahuachapan, Ahuachapan. However the club was not allowed to play at the Estadio Simeon Magana was to unable to meet the requirements to play dor the first part of the Clausura 2019 therefore they moved their games to the Estadio Ana Mercedes Campos, Sonsonate. However they received approval to return back to the Estadio Simeon Magana.
Club records
First victory in the Primera Division for Once Deportivo: 2-1 Isidro Metapan, August 17, 2019
First goalscorer for Once Deportivo:Anthony Roque v Aguila, August 10, 2019
First goalscorer in the Primera Division for Once Deportivo: Anthony Roque v Aguila, August 10, 2019
