Born in Plymouth, Will-Griff John was brought up in Ferndale in the Rhondda Valley. He went to Bridgend College and was in the same year as Dragons skipper Cory Hill and Cardiff Blues and Wales utility back, Matthew Morgan.
He won caps for Wales at U16, U18 and U20 levels and he played at the 2012 Junior World Championship. Having originally started as a No 8, he was converted to tight head prop while at the Cardiff Blues Academy. He made one appearance for the Blues in the Anglo-Welsh Cup and made 188 appearances for Cardif in the Welsh Premiership between 2010-13.
Released by the Blues in 2013, he went to New Zealand and played 18 times for Northland in the Mitre 10 Cup. He then opted to join Doncaster Knights in the English Championship, where he added a further 50 appearances to his playing CV. Having gained a reputation as a destructive scrummager, he caught the attention of Sale Sharks director of rugby Steve Diamond, who offered him a contract in 2017. Since then he has become one of the mainstays of the Sale pack.