In late August 2017, Oliver underwent surgery for a shoulder injury and was ruled out until early 2018. He made his return for Munster on 1 January 2018, starting against Connacht in a 2017–18 Pro14 fixture and earning the Man-of-the-Match award in Munster's 39–13 win. He signed a new two-year deal with Munster in February 2018, advancing from a development to full contract.