Griffiths grew up in Western Australia and studied at the University of Melbourne, where he entered Trinity College as a scholar in 2001. In 2007 he co-founded the fundraising platform Ripple with Jehan Ratnatunga and Matthew Tilleard. It had early success but could not sustain itself.
He next ran the Shebeen, a bar in Melbourne's CBD that handed over all of its profit to charity. It closed too.
In 2012 Griffiths, Ratnatunga and Danny Alexander launched Who Gives A Crap with an Indiegogo campaign. Griffiths sat on a toilet for 50 hours. The goal was A$50,000 and the campaign raised A$93,000. First deliveries began in 2013, and a stalled retailer deal pushed the founders to sell direct to households online.
In 2020, during the toilet paper shortage, demand rose 1,100%. In the 2019-20 financial year the company donated A$5.85 million to partner organisations, and cumulative donations reached about A$8.3 million.