In 2009, while supporting Paolo Nutini on his Australian tour under Joe Echo, Gribbin met INXS keyboardist and songwriter Andrew Farriss at a house party in Sydney. Over the next 12 months, Farriss and Gribbin became close friends and in May 2011 the two songwriters got together for a songwriting session. The members of INXS were impressed with Gribbin’s vocal and songwriting ability and promptly asked him to audition for lead vocalist of their band. In November 2011, Gribbin performed his first show with INXS in Arequipa, Peru in front of 7,000 people and two nights later performed in front of 30,000 people, headlining the Personal Festival in Buenos Aires, Argentina. He replaced their former lead singer, J.D. Fortune.
Gribbin has performed 50+ shows as INXS' frontman. Two of the songs Gribbin co-wrote with Andrew Farris have been released by INXS. "Tiny Summer"was a free download single. The second single, "We Are United",was performed in Australia's capital city, Canberra, at the Australia Day celebrations in January 2012 in front of a television audience of one million, and was released to mark this occasion.