Bloomfield completed several years of clinical work and from 1996 specialised in public health medicine, concentrating on non-communicable diseases.
In 1997, he graduated from the University of Auckland with a Master of Public Health degree, with first-class honours.

Between 2004 and 2006, Bloomfield was the Ministry of Health's acting director of public health.
From 2006 to 2010, he was the ministry's chief public health adviser.

From late 2010 to late 2011, based at the World Health Organization in Geneva, Bloomfield worked on non-communicable disease prevention and control with a global focus.
From 2012 to 2015, he held leading positions across district health boards with Capital & Coast District, Hutt Valley, and Wairarapa.
From 2015 to 2018, Bloomfield was chief executive at Hutt Valley District Health Board.
In the first half of 2018, Bloomfield was seconded to the Capital & Coast District Health Board where he was interim chief executive.
Since 11 June 2018, he has been the chief executive of the country's Ministry of Health and the country's Director-General of Health.
Since he started as the ministry's Chief Executive he has attended a leadership programme at Saïd Business School at the University of Oxford.

Colleagues describe Bloomfield as "measured, methodical, calm and sensible".
Former health reporter Tess Nichol, writing for the American online magazine Slate, described him as "New Zealand’s current obsession, an unlikely heartthrob, a mild-mannered health care hero".
Former prime minister, Geoffrey Palmer, remarked about Bloomfield: "It is a long time since a public servant has become so well-known."

Perhaps in part due to the relative effectiveness of the COVID-19 measures taken by the New Zealand Government, Bloomfield has developed a cult following.
Facebook pages and merchandise have been created celebrating Bloomfield, and at least one person has had his image tattooed on their body.
When Bloomfield played for an invitational Centurions side in their 2020 rugby match against the Parliamentary team, children took placards to the game to support him.
Bloomfield chose the nickname "The Eliminator" for the match, in which he opened the scoring with the first try.
Bloomfield completed several years of clinical work and from 1996 specialised in public health medicine, concentrating on non-communicable diseases. In 1997, he graduated from the University of Auckland with a Master of Public Health degree, with first-class honours.
Between 2004 and 2006, Bloomfield was the Ministry of Health's acting director of public health. From 2006 to 2010, he was the ministry's chief public health adviser.
From late 2010 to late 2011, based at the World Health Organization in Geneva, Bloomfield worked on non-communicable disease prevention and control with a global focus. From 2012 to 2015, he held leading positions across district health boards with Capital & Coast District, Hutt Valley, and Wairarapa. From 2015 to 2018, Bloomfield was chief executive at Hutt Valley District Health Board. In the first half of 2018, Bloomfield was seconded to the Capital & Coast District Health Board where he was interim chief executive. Since 11 June 2018, he has been the chief executive of the country's Ministry of Health and the country's Director-General of Health. Since he started as the ministry's Chief Executive he has attended a leadership programme at Saïd Business School at the University of Oxford.
Colleagues describe Bloomfield as "measured, methodical, calm and sensible". Former health reporter Tess Nichol, writing for the American online magazine Slate, described him as "New Zealand’s current obsession, an unlikely heartthrob, a mild-mannered health care hero". Former prime minister, Geoffrey Palmer, remarked about Bloomfield: "It is a long time since a public servant has become so well-known."
Perhaps in part due to the relative effectiveness of the COVID-19 measures taken by the New Zealand Government, Bloomfield has developed a cult following. Facebook pages and merchandise have been created celebrating Bloomfield, and at least one person has had his image tattooed on their body. When Bloomfield played for an invitational Centurions side in their 2020 rugby match against the Parliamentary team, children took placards to the game to support him. Bloomfield chose the nickname "The Eliminator" for the match, in which he opened the scoring with the first try.
Ashley Bloomfield