Ranjna was the co-founder of Auckland's Tāmaki Health (formely Nirvana Health Group), New Zealand's largest independent primary health care network. Tāmaki Health serves over 300,000 registered patients and is the largest health provider for high-needs, Pacific Island and Māori audiences. Tāmaki Health also provides innovate and leading telehealth services.
She has extensive involvement in charitable and community groups for which she received a QSM in 2009 and ONZM in 2017.
In December 2014, in partnership with Counties Manukau Police and Sahaayta Counselling and Social Support, Ranjna established Gandhi Nivas, a violence prevention programme that tackles family violence by providing counselling and emergency housing to men referred to the service by police, community and self-referral. This program has seen 60% non-recidivism during the five years after receiving the service, and a social return on investment of $12.80 for every $1 invested.
Ranjna is also a trustee of Swaminarayan Hindu Temple in South Auckland which serves over 200 people a day and provides a free meal every Sunday to 500-800 people.
Ranjna has been inducted into the NZ Business of Fame and Co.OfWomen Hall of Fame. She has won Trademe New Zealander Innovation of the Year, Westpac Women of Influence – Community Hero, NEXT Women of the Year in Business and Innovation, IBA Businesswoman of the Year for 2011, the Deloitte Top 200 Visionary Leader award for 2016 and the EY Entrepreneur of the Year Master Category in 2016. She is also a Patron of NZ Police Recruit Wing 330.