On 26 December 2015, Mannone started ahead of Pantilimon in a 4–1 defeat at Manchester City. He retained his place in the following match, a 0–1 home defeat to Liverpool, and was praised by manager Sam Allardyce after the game. After Pantilimon was transferred to Watford in January 2016, Mannone remained first choice over Jordan Pickford for the rest of the season, as Sunderland fought an ultimately successful battle against relegation, with their safety eventually being confirmed with a 3–0 home victory over Everton on 11 May 2016.