Born 23 March 1964 in Hāwera, New Zealand, Mitchell was a pupil at Francis Douglas Memorial College in New Plymouth when he made the first XV; he was a member of the NZ secondary schools basketball team from 1981 to 1983.

[citation needed] Overall, he played 134 games for Waikato, including a record 86 times as captain, scoring 335 points from 67 tries.

In the off-season, Mitchell played club rugby in France and Ireland, which included a stint with Garryowen in the All-Ireland League.

He later captained the side three times, all resulting in victories – against a Scottish Development XV 31–12, England Emerging Players 30–19 and Combined Services 13–3.

[citation needed] In late 2000 Mitchell returned to New Zealand for his appointment as the new head coach of the Chiefs in the Super 12,[6] and he led the side to sixth in the table.

[7] Just a month after being appointed as head coach, Mitchell's first match in charge was against Ireland in Dublin, which saw the All Blacks win 40–29, before going onto beat Scotland 37–6, and Argentina 24–20.

Mitchell led the All Blacks to a third-place finish at the 2003 Rugby World Cup, with victories over Italy, Canada, Tonga and Wales in the group stage to finish top of Pool D. The All Blacks beat the Springboks 29–9 in the quarterfinals, but lost to hosts Australia in the semifinal 22–10.

The NZRU cited Mitchell's difficult relationships with the media and with sponsors as the main reasons for searching for other head coaching candidates, rather than the performance of the team.

[17] Following the 2015 Rugby World Cup, Mitchell applied for the vacant head coach position of the England national team, but Eddie Jones got the role instead.

On 20 February, USA went top of the table with a 64–0 victory over Chile, however the States failed to keep hold of that position a week later when they were surprisingly beaten by Brazil in Barueri 24–23, with a last minute penalty to the Brazilians.

In March 2017, Mitchell led the United States to their first ever Americas Rugby Championship title, with victories over Brazil (51–3), Canada (51–34), Chile (57–9) and Uruguay (29–23) heading into the final week.

Both the United States and Argentina XV were level on points leading into the Championship decider in the final week, which saw them draw for the second consecutive year – a bonus-point try in overtime to level the score and see the United States finish with 22 points on the table to Argentina's 21.

This came after they drew the first leg, Canada at home, 28–28, before the return fixture the following week in San Diego, which saw the Eagles win 52–16.

In September 2018, Mitchell left his post with the South African franchise, and became defensive coach for the England national team.

He experienced tremendous success and helped England mount an incredible World Cup campaign that saw them reach the final in 2019.