Born in Mumbai, Ajaz Patel moved with his family to New Zealand at the age of eight. Initially a left-arm seam bowler, he eventually transitioned into a slow left-arm orthodox spin bowler.

Patel's international career took off in July 2018 when he was named to New Zealand's Test squad for their series against Pakistan in the UAE. He was later included in the T20I squad for the same series and made his T20I debut in October. Although he was added to New Zealand's ODI squad during the same tour, he did not play in the ODI series. Patel made his Test debut in November against Pakistan, where he claimed five wickets in the second innings, helping New Zealand secure a narrow four-run victory. His impressive performance earned him the Player of the Match award.

In May 2020, New Zealand Cricket awarded Patel a central contract for the 2020–21 season. He truly announced himself on the international stage in the second Test against India in December 2021. In that match, he became just the third bowler in history to take all ten wickets in an innings of a Test match, joining Jim Laker and Anil Kumble in this extraordinary achievement. However, despite Patel’s record-breaking performance, New Zealand suffered a defeat, making him the first bowler to achieve the remarkable feat and still end up on the losing side.