Penarth RFC was founded in 1879 by Cyril and Llewellyn Batchelor, sons of the John Batchelor whose statue stands in The Hayes, Cardiff. Originally known as the Batchelor XV the team amalgamated with Penarth Dreadnoughts in 1882 and renamed as Penarth Football Club - soccer being known as Association football at the time. Locally the team became known as the "Donkey Island Butcher Boys", a nickname that occasionally remains to this day, along with the familial name of the "Seasiders". Early games had been played on land owned by Glebe Street butcher and early club benefactor, David Cornwall and located on the field where All Saints Church now stands in Victoria Square.
In 1891 the pitch was relocated to land owned by the Earl of Plymouth roughly where the Masonic Hall now stands on Stanwell Road, behind Victoria School. During the 1914 - 1918 Great War the pitch was dug up and used to grow vegetables for local residents. During the war seventeen Penarth RFC players were killed while performing their army service in France and are commemorated by the Memorial Stand above the clubhouse’s Long Room. At the end of the war the club moved again, this time to a field on Lavernock Road opposite the Penarth County Grammar School sports field, owned by Fred Davies of Morristown. After a brief spell on Thurston’s field (where Erw Delyn School now stands) the team finally relocated to its permanent home at the Athletics Field, provided to the community by the Earl of Plymouth for use by the town's rugby, cricket and hockey teams.
The earliest Penarth RFC players to achieve international caps for Wales were Richard Garrett (between 1888 – 1892), George Rowles (1892) and John M C Dyke (1906). Three Penarth players were selected to tour New Zealand with the 1908 Anglo-Welsh team, they were brothers Len and Ralph Thomas and John Dyke (Ralph Thomas was injured prior to embarcation and was not able to join the tour). Also on the Anglo-Welsh team was former Penarth captain Reggie Gibbs, by then playing with Cardiff RFC. Annually between 1910 and 1913 Penarth RFC toured France playing matches against teams from Tarbes, Bayonne pau Brive, Bordeaux and Le Havre.
Tommy Garrett, the son of Richard Garrett together with Tommy Crossman played for Wales against England in a school-boy international during 1909. Both their international caps and Tommy Crossman’s jersey are held in the club archive. Other players who gained their Welsh international caps from Penarth were Mel Rosser (1924), Jack Bassett (1929 – 1932). Gomer Hughes (1934), Frank Trott (1939 - 1945 wartime international games), Elwyn Jones played for the Barbarians against the 1963 All Blacks. Jack Bassett was also selected to tour with the British Lions in 1930 playing in all five tests matches before captaining Wales on nine separate occasions and also playing for the Barbarians. Glamorgan and England cricketer and all-round sportsman, Austin Matthews also played rugger for Penarth RFC and later Northampton RFC. In 1929, during his time with Penarth, Austin was a final Welsh rugby trialist and his cap is held in the Penarth Club's archive. Matthews captained Northampton RFC between 1935 - 1937. His Northampton cap is also lodged with the Penarth RFC archive together with the cap gained by Austin's father, Frederick, as a final Welsh rugby trialist in 1896. Austin also represented Wales at table tennis.
Until a steady slow decline in the club's fortunes and a major reorganisation of Welsh rugby during the mid 1970s, Penarth RFC continued to be a regular force in the 'Welsh First Class Clubs' playing their weekly matches against top quality sides from Cardiff, Newport, Swansea, Bridgend, Neath, Pontypridd, Pontypool, Bath and Gloucester.
The highlight of the club's year was the traditional hosting of the world-famous Barbarians Football Club at annual Good Friday fixtures that were always attended by enthusiastic capacity crowds. This fixture marked the start of the "Baa-Baas" annual South Wales tour from their "spiritual home" of Penarth, which also encompassed playing Cardiff RFC on the Saturday, Swansea RFC on Easter Monday and Newport RFC on the Tuesday.
The non-match day of Easter Sunday would always see the Barbarians playing golf at the Glamorganshire Golf Club, in Penarth, while the former Esplanade Hotel, that was located on the seafront at Penarth would host the gala party for the trip, sponsored by the Penarth RFC club. The first match took place in 1901, and over the next 75 encounters, Penarth won eleven games, drew four and lost 60. Between 1920 and the first Athletics Field game in 1925 the Good Friday games were hosted on Penarth County Grammar School’s sports field. The final Penarth v Barbarians game was played in 1986 by which time the Penarth club had slipped from its former prominent position in Welsh rugby.
However, a special commemorative game, recognising the 100 years since the first Good Friday match, took place in 2001 and was played at the Athletic Field next to the Penarth clubhouse the day before the Barbarians played Wales at the Millennium Stadium. Gary Teichmann captain of both the South African International squad and the Barbarians, unveiled a plaque at the clubhouse to mark the event.
Following the last Baa-Baas game on Good Friday 1986 the club was fortunate enough to secure one fixture against the French Barbarians in October 1987. Penarth RFC is currently the only Welsh club side to have played against the premier French tourists.
The club celebrated its 125th anniversary during the 2004-05 season. During the course of the year a number of special games were played, including fixtures against the Glamorgan County, Welsh Academicals, and Coal Island Eire sides.
Former Penarth Youth RFC player Jamie Ringer took part in the 2006 Commonwealth Games in Melbourne, as part of the Wales national rugby union team (sevens). Also that year former Wales rugby Captain Hemi Taylor, a playing member of Penarth RFC senior team, presented the club's highly successful youth section with a cheque for £1,500 on behalf of the ‘Bears Golf Society'. Originally the Bears, who formed in 1982, raised money only for the senior Penarth team
After a hard and concerted campaign in 2006-07, Penarth RFC won promotion to the Welsh National League Division 3 South-East by finishing runner-up in Division 4 South-East.