No written records are available concerning the origins of the Club but it is believed that it was formed in the 1870's by two Yorkshiremen who were installing machinery in the local woollen mill. (The same men are supposed to have started the Langholm Club.) Kelso Rugby Club was formed in 1876 and one of their first games was against Earlston, the result being a draw. On 7th March 1879 Earlston played Kelso at Kelso in one of the first matches staged under electric floodlights.
The Club also played in the first Melrose Sevens in 1883. In the early years the Club's pitch was located at the Georgefield Road close to where the school pitches are today. In 1921 the present pitch at the Haugh (a Scottish word meaning river meadow) was leased from A. Brownlie, Timber Merchants. Two years later the first Clubhouse was erected. On 1st September 1923 the first Earlston Seven-a-Side Tournament was held and in 1935 the present cup, reputed to be one of the most valuable on the Border Sevens circuit, was purchased thanks to subscriptions from Club supporters. In 1984 the Sevens date was switched to the Spring - the Sunday prior to the first Monday in May. The 1939 Sevens tournament was cancelled as World War 2 started the next day. No organised rugby took place until the war ended.
Throughout the war the pitch and clubhouse were requisitioned by the military. Approximately one third of the pitch was dug out and concrete laid to make "hull-down" park for tanks (Polish Lancers) stationed in the area preparing for D-Day. It was 1948 before the playing surface was full restored and matches were played on a temporary pitch on another part of the Haugh. From 1946 to 1948 the sevens were held at the Greenyards, Melrose - the Melrose Club refusing any offers of payment.
In 1968 the first major extension was carried out on the Clubhouse - with nearly all of the work being done by voluntary labour of members and some non-members. The first licensed bar was installed at this time. In 1984-85 the Club President and Vice President (J. Fairbairn and R Kerr) held discussions with Mr A Brownlie Jnr., and the last named agreed to sell the pitch to the Club at what can best be described as favourable terms. The Club lawyer, J Cullen, handled the transaction also at favourable terms. A further major extension to the Clubhouse (the present layout) was completed in 1988. Again most of the work was done by voluntary labour thus saving the Club a large amount of capital.