Paul Griffen was raised in New Zealand and played his early rugby at Blaketown RFC and at Linwood RFC, later representing the West Coast in 1993 and Canterbury in 1997 in the National Provincial Championship. In 1999, he left New Zealand and joined Partenope of Naples, a second tier Italian side where he played for one season. Griffen then transferred to Calvisano for the start of the 2000–01 season, appearing in the Super 10. He was an integral member of the team that won the Super 10 in 2004–2005 & 2007–2008 seasons and the Coppa Italia in the 2003–2004 season.