On 21 January 2014, after only three Copa del Rey matches to his credit, Ustari was released by the Andalusians and signed a six-month contract with Sunderland. He made his debut for his new team four days later, keeping a clean sheet in a 1–0 home win against Kidderminster Harriers in the fourth round of the FA Cup. He was also in goal in the following game in the tournament, and the result was the same against Southampton, and was an unused substitute on 2 March in the final loss to Manchester City at Wembley Stadium.