At a meeting in the local Royal British Legion Hall in April 1954, a dozen people attended and agreed that a club should be formed. An application was made to enter the Junior League for the 1954-55 season. The application was accepted by the Ulster Branch. Membership for the club grew quickly with players coming from all over County Down, Belfast and the Mournes region. It was at this point that the Club started to gather pace and a pitch was required due to the growing player base. A pitch was rented from a local farmer at Ballykine. Even though the grounds had no changing rooms or showers it did the job of providing Ballynahinch club with a home. In 1964 the club enjoyed success with the winning of the Ulster Towns Cup. The Ulster Junior Cup was won consecutively in 1966 and 1967.
An increasing player and fan base meant that proper grounds were required. In August 1970, at the cost of £6,500, the current playing facilities at Ballymacarn Park were purchased. The 16-acre (65,000 m2) site soon had its own clubhouse in front of the 1st XV pitch. It was from this point that the club grew to field 7 teams. The 1st XV went on to be one of the top teams in Ulster Junior League rugby for the next 10 years. Senior status In the early 1990s, Irish rugby underwent changes with the introduction of professionalism. Ballynahinch for many years had campaigned for Senior status. An open promotion and relegation system was introduced and in 1995 Ballynahinch achieved their goal. As a Senior club they won promotion from All Ireland League Division 4 to Division 3 in 1996-97 season. The following season a further promotion was gained to All Ireland Division 2. The 1998-99 season saw the successful run come to an end when they got relegated back to Division 3, only to go back up again after the 2000-01 season. Mid-table finishes were achieved in Division 2 until the 2005-06 when the club was once again relegated to Division 3. Ballynahinch played Division 2 rugby again in the 2007-08 season, with another mid-table finish after winning promotion in the 2006-07 campaign.
In 2008-09 the club had its most successful season, winning the AIB All-Ireland Cup by beating Division 1 team Cork Constitution in the final, and winning the Ulster Senior League, Ulster Senior Cup, the Division 2 Championship and promotion to Division 1 of the AIB League. The 2009-10 season was not as successful with the 1stXV failing to remain in Division 1B, but as the 2010-11 season is a about to get underway the goal is to secure promotion back into Division 1 for 2011-12.
Morale in the Club was high and the 1st XV did win promotion back to AIL Division 1B in 2010-11 and the following season, 2011-12, finished a very creditable 4th place in Division 1B. In 2012-13 the Club, by winning Division 1B of the AIL and also the Ulster Senior League and promotion to Division 1A of the AIL, achieved its long term aim of having every team