The powerful 6ft 3in tall centre graduated from the Ysgol Bro Morgannwg to represent the Wales U18 and U20 teams before moving into Warren Gatland’s senior side in 2013. He won the first of his six caps against Argentina in the autumn series that year while still only 20.
He damaged his shoulder late on in a 40-6 victory at the then Millennium Stadium and missed the rest off the series and the 2014 Six Nations campaign. His second cap came a year later as a replacement in the autumn defeat to Australia.
He was on the winning side in his next four appearances, including a World Cup triumph in Cardiff against Uruguay in 2015. In that game he scored a first-half hat-trick before limping off with a hamstring injury after 54 minutes that ruled him out of the remainder the tour tournament.
He started in both games on the 2017 summer tour that saw Wales beat Tonga in Auckland and Samoa in Apia. He also picked up a win over the All Blacks, 9-6, at the 2012 Junior World Championships and was in the Wales Sevens squad in 2012-13
Allen started for Wales U20 against New Zealand U20 on 8 June 2012, Wales defeating them 9–6 to earn their first win at this age group. He was also selected in the Wales Sevens squad for 2012-13
Having made his professional debut for Cardiff Blues in an Anglo-Welsh fixture against Newcastle Falcons at the age of 18 in October 2011 and went on to play more than 50 times for his home region. He switched to the Ospreys in 2017 and played a further 33 times for them in an injury hit stay.
He moved to the Dragons in 2021, where injuries once again plagued his career and reduced his playing time.
“I’ve known Cory for many years, and he’s been a fantastic rugby player. He’s worked hard to return to full fitness and so we’re all disappointed that he’s now had to make this decision,” said Dragons head coach Dai Flanagan.
“Cory has always been a popular member of the squad and although he has not featured for us, he’s played a full role here, helping develop young players and passing on his experience and knowledge.
“He’s been an asset for us with his work in and around the club and leaves us with our best wishes for the next chapter in his life.”