Crotty has previously played for the Crusaders in the Super Rugby competition [1] and Canterbury in the ITM Cup, captaining both teams.

Crotty made his international debut for New Zealand in the 47–29 win against Australia in Sydney on 17 August 2013, replacing veteran Ma'a Nonu off the bench in the 62nd minute.

He was retained in the All Blacks' 2014 squad and made his first international start on 23 August 2014, in the second Bledisloe Cup test against the Wallabies during the 2014 Rugby Championship.

After the retirements of Nonu and Smith in 2015, Crotty was re-selected for New Zealand in 2016, and was named as the starting inside centre for the first test match of the year against Wales.

Crotty suffered a knee injury in the All Blacks' historic 29-40 loss to Ireland in Chicago on 5 November 2016 and was subbed off only 26 minutes in and replaced by Malakai Fekitoa.

Crotty returned from injury on 26 November to start in the final test of the year, partnering rookie Anton Lienert-Brown in the midfield as the All Blacks beat France 24-19 to end their 2016 season.

The 2017 season ended in disappointment for Crotty after an average performance against Scotland as well as the following week when he was subbed off only 19 minutes into the All Blacks' 33-18 win over Wales on 25 November 2017 for a concussion test.

This was not Crotty's only injury through 2018, as he was subbed from the field only 12 minutes into the All Blacks' first Bledisloe Cup test of 2018, having accumulated a sixth concussion in the space of 18 months.

[4] Although this was the case, Williams left the field injured late in the first half, with Crotty making immediate impact, setting up Damian McKenzie for New Zealand's only try against England in their 16-15 win.

In 2019, Crotty confirmed that he would leave New Zealand at the end of the 2019 Rugby World Cup, to play for a Funabashi-based team, the Kubota Spears, in the Japanese Top League.

Crotty played his 150th game for the Crusaders on 8 June, kicking a goal to convert his last-minute try against the Melbourne Rebels, to celebrate his achievement, as well as the 66-0 win.

[7][8] On 28 August 2019, All Blacks Head Coach, Steve Hansen, named Crotty as one of 31 players in New Zealand's squad for the 2019 Rugby World Cup.

Crotty started in the Bronze Final, against Wales, with long-term midfield partner, Sonny Bill Williams, as well as fellow retiring players, Kieran Read, Ben Smith and Matt Todd.