Alun Wyn Jones was part of the Wales U21 Grand Slam winning team in 2005 and won the Principality Building Society's Best Newcomer award in the Premiership with Swansea for the 2005–2006 season.

He joined the Ospreys region at the start of the 2005–2006 season, making fifteen appearances in his first season with the region. Jones appeared on 25 occasions for the Ospreys during the 2006–2007 season and secured two tries.

His superb form in his debut season with the region led to Jones being picked for Wales's summer tour to Argentina in 2006, where he played in both games at blindside flanker, gaining his first caps at senior level. Able to play at lock or blindside flanker, Jones has covered both positions for Wales and the Ospreys.

Jones was named in the national squad for the 2006 Invesco Perpetual Series; he started against the Pacific Islanders and came off the bench for the clashes with Canada and New Zealand. Jones also featured for Wales in every game of the 2007 RBS Six Nations.

Jones was rested from the squad for the two-Test tour of Australia in May 2007; in June he was named in Gareth Jenkins's 41-man preliminary Rugby World Cup 2007 summer training squad. In August, Jones played in the defeat to England at Twickenham and after being named in Jenkins's final RWC squad of 30, played in the Invesco Perpetual Summer Series matches against Argentina and France, scoring a try in the victory over the Pumas.

Jones made try-scoring appearances in Wales's Pool B encounters with Canada and Japan, and also made the starting line-up for the two defeats at the hands of Australia and Fiji. He was selected in the starting XV for the Prince William Cup match against South Africa in November 2007 by then Caretaker Coach Nigel Davies.

January 2008 saw Jones included in Warren Gatand's RBS Six Nations squad; the lock made three appearances in the Grand Slam winning tournament against England, Ireland and France, missing out on the remaining fixtures due to an injury picked up after the initial match of the campaign.

He was back in action in November 2008 when he was one of Wales’s most consistent performers against South Africa, New Zealand and Australia. After a fine domestic season, Jones was selected for the summer Lions tour of South Africa where he partnered Paul O’Connell in each of the three Tests.