Scannell made his senior Munster debut on 1 November 2014, starting at inside centre against Cardiff Blues in a 2014–15 Pro12 fixture. He started at fly-half against Cardiff Blues on 14 February 2015. Scannell was nominated for the 2015 John McCarthy Award for Academy Player of the Year in April 2015. On 14 November 2015, Scannell made his European Rugby Champions Cup debut for Munster, coming off the bench in their opening 2015–16 pool game against Benetton.