Green, 24, from Paarl in the Western Cape, represented South Africa in the contest held on Sunday evening in Bangkok, Thailand, against contestants from 93 other countries.
She made the top three where she was up against Miss Philippines Catriona Gray and Miss Venezuela Sthefany Gutiérrez .
Former Miss Universe, South African Demi-Leigh Nel-Peters, a former Miss South Africa, was on hand to crown her successor. Instead of a long gown, Nel-Peters opted to wear a white pantsuit with bedazzled lapels and wide leg pants in her final walk through.
She said she knew the day was coming (when she would hand over the crown) but it was still sad to say goodbye.
She plans to continue her advocacy after her reign: “No woman deserves to be a victim of violence and crime,” she told news reporters, saying they should feel safe and strong. She started the Unbreakable campaign after experiencing the trauma of an attempted hijacking in Joburg in 2017.
Gray, 24, became the fourth Filipino to be named Miss Universe. Her father is Scottish.
Green was gracious in her praise for Catriona and the other contestants and said she had made lifelong friends. She thanked their hosts in Thailand and the fans at home for all their support. She also promoted her #BreakTheStigma at Miss Universe which has been successful at raising awareness around TB.
Previously Tamaryn spoke at the UN General Assembly meeting on tuberculosis and the Union Conference on Lung Disease at The Hague where she told her story and her battle with TB.
When Tamaryn was crowned in May she was a final-year medical student at the University of Cape Town. She is set on specialising in paediatrics once she resumes her studies after her reign.