[2][3] George played for local team Hertford Rugby Football Club in his youth,[4] until he was asked to join the Saracens Academy.

[8] He had a short loan spell at Southend Saxons in the lower tiers of English rugby in 2008–09, however quickly caught the attention of Bobby Walsh in the Saracens management team to return the following season.

[9] In November 2009 George made his professional club debut for the Saracens first team against Northampton Saints in the Anglo-Welsh Cup.

[21] George scored a try in the Championship play-off final as Saracens defeated Ealing Trailfinders to gain promotion and an immediate return to the top flight.

[5] In January 2016, George was announced in new coach Eddie Jones' first senior England squad for the 2016 Six Nations Championship[34] and on 6 February 2016 made his first tournament appearance as a replacement for captain Hartley in their opening round 15–9 victory against Scotland.

[36] Later that year George scored his first international try in the final test of their summer tour of Australia to complete a series whitewash.

[37] England retained their title during the 2017 Six Nations Championship,[38] missing out on a consecutive grand slam with defeat in the final game away to Ireland which also brought an end to a record equalling eighteen successive Test victories.

[40] He started all three knockout games against Australia in the quarter-final,[41] victory over New Zealand in the semi-final[42] and defeat to South Africa in the final as England finished runners up.

[44] The following month saw him become the first hooker to score a hat-trick for the England men's team in their opening fixture of the Autumn Nations Cup against Georgia.

[47] In November 2024, he earned his 97th cap for England, captaining the side and scoring two tries in a 59–14 win over Japan during their final fixture of the 2024 Autumn Nations Series.

[48][49] In January 2025, although he was selected for the senior training squad, he relinquished the England captaincy to Saracens teammate Maro Itoje for the 2025 Six Nations.