San Antonio Unido

Early years: 1958–1990

Coquimbo Unido was founded on 30 August 1958 in the port city of Coquimbo, following the consolidation of local football organizations that sought to establish a professional representative for the city. The club's statutes had been approved earlier that year, while its legal constitution was formalized through a public deed on 30 August. In February 1959, the Asociación Central de Fútbol approved Coquimbo Unido's admission to professional football.

After several seasons in the second tier, Coquimbo won the Segunda División championship in 1962 and earned its first promotion to the Primera División, making its top-flight debut in 1963. The club subsequently alternated between the first and second divisions, winning another second-tier championship in 1977.

Following another period outside the top flight, Coquimbo finished runner-up in the 1990 Segunda División and secured promotion for the 1991 season. This return marked the beginning of one of the most successful periods in the club's history.

First international era

Under manager José Sulantay, Coquimbo Unido produced its best league campaign to that point in 1991, finishing second in the Primera División behind Colo-Colo. The result qualified the club for the 1992 Copa Libertadores, becoming the first team from the Coquimbo Region to participate in the competition. In the Libertadores, Coquimbo shared a group with Colo-Colo, Universidad Católica, San Lorenzo de Almagro and Newell's Old Boys, but was eliminated in the group stage.

Coquimbo remained in Primera División throughout the 1990s and early 2000s. Another major opportunity came in the 2005 Apertura, when the team, coached by Raúl Toro, reached the championship final after eliminating Huachipato in the semi-finals. Coquimbo faced Unión Española in the final, losing the first leg 1–0 and the return match 3–2 at the Estadio Francisco Sánchez Rumoroso, finishing as tournament runner-up.

The long spell in the top division ended in 2007. After sixteen consecutive seasons in Primera División, Coquimbo was relegated following a difficult Apertura and Clausura campaign.

Primera B and return

Coquimbo spent the following eleven seasons in Primera B, repeatedly coming close to promotion. In 2008, the club won the Clausura tournament but lost the subsequent promotion series, first against Deportes Iquique and later against Universidad de Concepción. In 2014, Coquimbo again won a Clausura competition, but was eliminated by San Luis de Quillota on penalties in the promotion play-offs.

The club endured one of its most difficult seasons in 2015–16, beginning the campaign with seventeen matches without a victory and entering the final round in danger of relegation to the third tier. A 4–2 victory over Barnechea ultimately preserved its Primera B status.

The breakthrough came in 2018 under Argentine manager Patricio Graff. Coquimbo led the championship from the second half of the season and secured the Primera B title with a 1–0 victory over Deportes Puerto Montt at a sold-out Estadio Francisco Sánchez Rumoroso. The team finished with 57 points and returned to Primera División after an eleven-year absence.

Continental success

Coquimbo established itself quickly after returning to the top flight. Its 2019 league campaign earned qualification for the 2020 Copa Sudamericana, marking the club's first international appearance since the 1992 Copa Libertadores.

The 2020 Copa Sudamericana became the most successful international campaign in the club's history. Coquimbo eliminated Aragua, Estudiantes de Mérida, Sport Huancayo and Junior to reach the semi-finals. In the semi-final, Coquimbo drew 0–0 with eventual champions Defensa y Justicia in the first leg before losing the return match 4–2 in Argentina.

The continental success contrasted sharply with the domestic campaign. A congested schedule and poor league results left Coquimbo at the bottom of the 2020 Primera División standings, and the club was relegated to Primera B at the end of the season.

The stay in the second tier lasted only one year. Coached by Héctor Tapia, and with a squad that included Esteban Paredes, Jean Beausejour and Carlos Carmona, Coquimbo won the 2021 Primera B championship. A 2–1 victory over Fernández Vial on the final matchday secured the title with 55 points and an immediate return to Primera División.

First league title

After narrowly avoiding another relegation in 2022, Coquimbo gradually re-established itself in the upper half of the Primera División. A strong 2023 season secured qualification for the 2024 Copa Sudamericana, where the club returned to continental competition and faced teams including Racing Club and Red Bull Bragantino.

The club reached a historic peak in 2025 under manager Esteban González. Coquimbo emerged as the dominant team of the Primera División, producing a fourteen-match winning streak during the campaign. On 2 November, a 2–0 home victory over Unión La Calera made the club mathematically unreachable with four matches remaining and secured the first top-flight championship in its history. Coquimbo completed the season with 75 points from 30 matches, recording 23 victories, six draws and only one defeat.