His father, Victor Greenwich Dadianov (formerly the Honorary Consul-General of Georgia in Sydney, 2004–2013), was born Prince Victor Dadianov of the princely Georgian Dadiani family [citation needed] but his mother changed the name to Greenwich after they moved as refugees to New Zealand from Russia after the Second World War.

From his family residence in Circular Quay, Greenwich was educated at Sydney Grammar School and completed a Bachelor of Arts in Human Resource Management and Russian Studies at the University of New South Wales.

Before entering politics, Greenwich was a prominent LGBT rights activist and led Australian Marriage Equality (AME).

[6] Prior to running for office, Greenwich was the national convener of AME from 2009, and in 2010 was named as one of Samesame.com.au's 25 most influential gay and lesbian Australians.

[7] In May 2012, Greenwich married his German Australian long-term partner, Victor Hoeld, in Argentina, where same-sex marriage was already legal.

[10] For WorldPride, Greenwich swapped his signature casual suit and shirt for a tuxedo with green tulle in a display that was hosted in the QVB.

Judge David O'Callaghan found that the tweet was defamatory because it made Greenwich out to be a person that "engages in disgusting sexual activities".