In the month of August 1920 Foot Ball Club Empoli and the football club Unione Sportiva Empoli were born. Following the participation in an event at San Miniato, the two were merged into one locally-based football team. In the following season the new club, after gaining membership in the Italian Football Federation (FIGC) approved with the Tuscan Regional Committee, was incorporated into group A in the Tuscan Promozione 1921-22. The team took part due to financial difficulties but decided to go to Terza Categoria's league. Terza Categoria. In that league, the team was second within the A group.
In the 1922-23 campaign, Empoli was second in the Group A in the Terza Categoria. They were admitted to the finals after having won the playoff in Florence that took place on the 15th of April 1923, against Pontedera 1-1. The season ended with 3rd place finish in the final of the group.
The subsequent three seasons, from 1923 until 1926 Empoli was still playing for the Tuscan third division. In 1926-27 period, Empoli took the title of Group A division in Tuscany and was then admitted into the finals of interregional competition because of a fourth position in Group G and a fourth place in Group G, the Tuscans were elevated to the North Division of the Second Division 1927-28, which was the third Italian football league in the time. The following season, Empoli was placed into Group C of the North Division, which concluded in fourth position however, due to financial reasons, the team were not invited to play in the next tournament of Prima Divisione. The team following the downgrading of the Seconda Divisione from third to fourth level. However, the following season, during the 1928-1929 Seconda Divisione, the club gained promotion, winning the Tuscan championship and then reverted into it's North Division of Prima Divisione.
Empoli was part of the Prima Divisione, later Serie C, until the 1935-36 season, in which Empoli's team was disbanded halfway into the season due to the call to arms of the players. Empoli began to compete again in the Prima Division the following season under the name OND Empoli, with the colors blue and gray. the team was crowned the Tuscan Group A, gaining the right to play in Serie C. Until the closure due to the effects of conflict, Empoli played in Serie C and achieved a top results of sixth place in 1938-39. In the meantime, the club was changed to OND Interaziendale Italo Gambaccioni Section Soccer between 1938 and 1941, and then it changed its name in the year 1941 to Associazione Calcio Empol. On the 15th of September, 1935 Empoli made its debut in the Coppa Italia, winning 1-0 in a victory at home against Pontedera.
Following World War II, Empoli adopted the name of the club that was previously Empoli Foot Ball Club following having been named Sports Group Azelio Landi for only a short period of time, from October to November 1944 and then was accepted into Serie B thanks to a third-place finish during the 1946-45 season. For Serie B, Empoli played for four seasons consecutively which ended in third position in the 1946-47 campaign. Empoli was relegated that, at the time, had adopted the color blue took place at the end of the 1949-50's championship. The permanent status in Serie C lasted for six seasons. During August of 1955, they had to sell many of its players. Then, at the close of the 1955-56 season the Tuscan side was sent into Serie D. After three seasons in the fourth division in 1959-60, the Azzurri could be relegated to regional league after finishing in 15th place, which was the same level as Carrarese, and Rieti. The club was able to avoid the relegation process, playing against Carrarese before beating Lazio and Lazio in Pesaro and scoring an unassisted goal by Vezzosi. In the 1960-61 season, Empoli returned to the third division in Italian football, however for just one season, and again suffered the fate of relegation.
The club was relegated back to Serie C on 9 June 1963, after having defeated Tempio 2 to 0 during the play-offs in Genoa. The club's status in the third division of Italian football, which was then referred to as Serie C1, lasted for twenty years up to in the season 1982-1983.