A product of the Pontypridd Youth Team, Ceri Sweeney made his debut for Wales against England in the Six Nations Championship in 2003, and played in three Rugby World Cup games later that year. Capped at U18, U19 and U21 levels, he toured Canada with the Wales Development squad in 2000 and made his Wales A debut as a replacement against England in 2002. Sweeney toured North America with Wales in 2005, scoring 42 points, including 17 conversions and a try against the USA. Sweeney scored Wales' only try against South Africa during the 2005 Invesco Perpetual Series. He was included in the national squad for the 2007 RBS Six Nations, making a substitute appearance against Scotland, and was also named in Gareth Jenkins's squad to tour Australia in May. He was an unused bench replacement in the first Test but appeared in the second Test loss as a replacement for the injured Jamie Robinson. After returning from the tour Down Under, Sweeney was announced in Wales's 41-man preliminary Rugby World Cup 2007 summer training squad. He played in the Test defeat to England at the start of August, was named in the final 30-man RWC squad and made an appearance in the Millennium Stadium clash against France in the Invesco Perpetual Summer Series. Sweeney made one appearance in the Rugby World Cup, as a replacement in Wales's victory over Japan at the Millennium Stadium. In November 2007 Sweeney was selected by Wales Caretaker Coach Nigel Davies as part of a 31 man squad ahead of the Prince William Cup clash with world champions South Africa. Although not originally selected in the matchday 22, he replaced Stephen Jones on the bench when he failed to recover from an injury and made a late substitute appearance in Wales's 34-12 defeat to the 'Boks.