In June 2015, it was announced that Mullally would be the next bishop of Crediton, a suffragan bishop in the Diocese of Exeter. On 22 July 2015, she was consecrated a bishop by Justin Welby, the archbishop of Canterbury, at Canterbury Cathedral.
In June 2015, it was declared that Mullally would be the next bishop of Crediton, a subordinate bishop in the Diocese of Exeter. On 22 July 2015, she was consecrated a bishop by Justin Welby, the archbishop of Canterbury, at Canterbury Cathedral.