Walsh was born and grew up in [[Wellington]] werewhere she went to school at [[St Mary's College, Wellington|St Mary's College]]<ref>{{cite news |title=Therese Walsh: 'Bigger the challenge, the better' |url=https://www.stuff.co.nz/dominion-post/sport/8996920/Therese-Walsh-Bigger-the-challenge-the-better |access-date=7 August 2022 |work=[[Stuff (website)|Stuff]] |date=2 August 2013 |language=en}}</ref><ref>{{cite news |last1=Carlisle |first1=Talia |title=Therese Walsh's rollercoaster ride |url=https://www.stuff.co.nz/dominion-post/news/69691878/therese-walshs-rollercoaster-ride |access-date=7 August 2022 |work=[[Stuff (website)|Stuff]] |date=1 July 2015 |language=en}}</ref> before studying accounting at [[Victoria University of Wellington]].<ref>{{Cite web|url=https://www.victoria.ac.nz/vbs/about/alumni/therese-walsh|title=Therese Walsh {{!}} Victoria Business School {{!}} Victoria University of Wellington|website=www.victoria.ac.nz|language=en|access-date=3 September 2017}}</ref> She started her professional life as a chartered accountant and auditor at [[KPMG]] in the city.<ref name=":2" /><ref name=":1">{{Cite web|url=http://www.globalwomen.org.nz/our-people/our-members/show/322/dame-therese-walsh|title=Our Members|website=www.globalwomen.org.nz|language=en|access-date=3 September 2017}}</ref><ref>{{Cite news|url=https://www.nbr.co.nz/article/new-director-appointed-asb-bank-180021|title=New director appointed – ASB Bank|date=13 October 2015|work=The National Business Review|access-date=3 September 2017|language=en}}</ref> In 2003 she moved to work for the [[New Zealand Rugby|New Zealand Rugby Union]] as general manager of corporate services and later as chief financial officer, and was then appointed to the team that worked on the winning bid to host the 2011 Rugby World Cup in New Zealand.<ref name=":1" /><ref name=":2">{{Cite web|url=https://management.co.nz/article/mw-cover-story-therese-walsh-career-crossbars|title=Therese Walsh: On Career Crossbars|date=27 September 2006|access-date=3 September 2017}}</ref>
Following her success with New Zealand rugby, Walsh became a director of [[New Zealand Cricket]]. She was the head of New Zealand's 2015 Cricket World Cup campaign and successfully negotiated for New Zealand to host a significant number of the games and events, including a semifinal held in Auckland, and the opening ceremony held in Christchurch.<ref>{{Cite web|url=http://www.stuff.co.nz/sport/cricket/68967117/therese-walsh-made-a-dame-in-queens-birthday-honours|title=Therese Walsh made a Dame in Queen's Birthday Honours|website=Stuff|access-date=3 September 2017}}</ref>