Born in Sutton Coldfield, England, he captained the Wales national team from 2002 to 2004, and also played for the British & Irish Lions on their tour of Australia in 2001.

[8] After Wales's elimination from the World Cup, having not received an acceptable offer from any of the five new Welsh regional sides,[9] Charvis signed for French second-tier side Tarbes on a contract that would take him through to the end of the 2003–04 season, when he was expected to return to Wales;[10] During the season, he expressed his intent to continue playing for Wales;[11] however, although he was part of the squad for the 2004 Six Nations Championship, his desire to continue his international career proved a stumbling block, and by the end of the tournament in March 2004, initial talks with three of the regions had reached an impasse.

[14] With his contract due to expire at the end of the season, talks began over a new deal but by May 2006, rumours surfaced that negotiations had broken down.

[23] Due to his involvement with Wales at the 2007 Rugby World Cup, Charvis missed the first five games of the Dragons' season in 2007–08, returning to action in the 19–13 away win over Edinburgh on 12 October 2007.

[24] He again scored back-to-back European tries in December 2007, crossing in the 35–33 away win at Benetton Treviso and 24–22 loss in the return game at Rodney Parade.

[25][26] That win over Benetton proved to be the Dragons' only one of the Heineken Cup campaign; they lost 25–0 in their final pool game against Perpignan on 19 January 2008, and Charvis suffered an injury that ruled him out for the next 10 weeks.

[29] Charvis signed a new one-year contract with the Dragons in July 2008 naming him as the team's contact and defence coach, while also reducing his playing commitments.

[30] He made his first appearance of the season off the bench in a 25–14 win over former club Newcastle in the Anglo-Welsh Cup on 3 October 2008, being named man of the match for his half-hour cameo.

[35] At the end of the season, after undergoing knee surgery, Charvis went full-time with his coaching duties at the Dragons, with a focus on defence.

In November 2007, Wales caretaker coach Nigel Davies included Charvis in his starting line-up for the inaugural Prince William Cup match with South Africa.

Despite the 34–12 defeat to the reigning world champions, Charvis scored his 22nd try for his country, making him the leading try scorer among all Welsh forwards (as of 2021).

[49] In 2023, Charvis was named as one of 295 former rugby players bringing a lawsuit against the sport's governing bodies over brain injuries sustained while playing.