While at Christchurch Boys' High School, Franks appeared alongside fellow All Blacks Colin Slade and Matt Todd, as well as former Crusaders Nasi Manu and Tim Bateman.

Franks won the 2017 Super Rugby season later in the year, with the Crusaders beating the Lions 25–17 at Ellis Park Stadium in Johannesburg.

[7] When Franks scored for the Crusaders against the Melbourne Rebels on Friday 26th April 2024 it was his first Super Rugby try in 14 years.

Franks became a regular starter for the All Blacks in 2010, supplanting the long-serving Neemia Tialata as New Zealand's first-choice tighthead prop.

Franks started in all of the knockout rounds, playing the full 80 minutes of the World Cup final against France on 23 October 2011, with the replacement prop, his brother Ben, not making the field.

According to the book, Cory Jane Winging It, Random Tales from the Right Wing, by former All Blacks teammate Cory Jane and Scott Stevenson, Franks and brother Ben are said to have celebrated the All Blacks Rugby World Cup 2011 victory by squatting the next day 280 kg for 10 Repetitions.

Franks started 12 times in 2012 with the exception of the third Bledisloe Cup test against Australia on 20 October as he replaced newcomer Charlie Faumuina off the bench as the All Blacks drew against the Wallabies 18-18.

Franks opened the 2015 Rugby World Cup final, against Australia on 31 October 2015, with a huge tackle on Wallabies fullback Israel Folau and played for 54 minutes before being replaced by Charlie Faumuina, who had returned from injury to take part in the tournament.

Franks had a good season in 2016, starting in all 12 of his test appearances which included a historic 29–40 loss to Ireland on 5 November 2016.

Prior to being selected for New Zealand's three-test series against the British and Irish Lions and Pasifika Challenge against Samoa, Franks' achilles' tendon was observed to be in noticeable pain.

Franks was immediately replaced on the match-day sheet by former Crusaders team-mate Nepo Laulala who had not played for the All Blacks since 2015 due to his own run of injury.

Franks was re-selected for New Zealand in 2018 for the three-test series against France for the June internationals, having recovered from injury during the 2018 Super Rugby season.

Franks became the first rugby player in history to reach 100 tests without scoring any points in his career, but performed well before being replaced by Ofa Tu'ungafasi in the 52nd minute.

On 28 August 2019, Franks was dropped from the All Blacks, missing out on the 31-man squad for the 2019 Rugby World Cup, with Nepo Laulala, Atu Moli, Joe Moody, Angus Ta'avao, and Ofa Tu'ungafasi being the preferred props.

[10][11] Having signed for Northampton earlier in 2019, Franks’ shock omission from the squad effectively ended his decorated international career.