The East Bengal Club, which was established on August 1, 1920, made its debut in the 1920 Hercules Cup, a seven-a-side competition, which it won. The Club then entered the Indian Foot Ball Association (IFA) league's Second Division and immediately announced its arrival by finishing third.

In 1924, East Bengal became joint champions of the Second Division with Cameroon B.

In 1925, East Bengal and Mohun Bagan clashed for the first time and East Bengal won 1-0. In the return match, Mohun Bagan avenged itself. Even today, 78 years later, this rivalry persists.

In 1942, East Bengal club secured its first league triumph, and the following year it won the IFA Shield. The club has never looked back since. In 1945 it won both the First Division league and the IFA Shield. The same year, the team thrashed BCCI Railways 11-0 in a Rovers Cup tie, the highest ever victory margin in its history. In the same match East Bengal's legendary Anglo-Burmese centre-forward Pagsley scored eight goals, establishing a record for the number of goals scored by an individual in a match. The following year, in the IFA Shield, East Bengal's S. Nayar established another record by scoring 36 goals, which still remains unbroken.

In 1951, East Bengal became the first Indian team to win the IFA Shield three times in a row (1949 to 1951). For this achievement, the English FA annual almanac of 1951-52 adjudged East Bengal the best Indian soccer club. Following this, on invitation, East Bengal became the first Indian football team to tour the Soviet Union and Romania. The club also has one of the best records of good performance against foreign teams. In 1948, East Bengal defeated the Chinese Olympic XI 2-0; in 1951, it was the Swedish FC Gothenburg that lost, 0-1; and in 1956, the Chinese Olympic XI lost again, 1-3. One of the most outstanding achievements of East Bengal was its 1-0 victory over PAS Club of Iran in the 1970 IFA Shield final. At the end of the match, over 80,000 fans of East Bengal lit up Eden Gardens by holding up flaming torches high over their heads. This was a glorious time for East Bengal, when it won the Calcutta football league for a record six times in a row, from 1970 to 1975.