Currently the Bishop of Tewkesbury the clergyman will take up his new job in Spring 2016.
Bishop Martyn, 47, was welcomed by the Diocese of Leicester Chief Executive, Jonathan Kerry.
"We are delighted to welcome Bishop Martyn and look forward to his leadership of the diocese and the diocesan team," he said.
The Dean of Leicester, David Monteith, said: "Bishop Martyn's experience of mission and ministry in rural and urban contexts makes him ideally placed to serve this diocese with wisdom, imagination and love. It will be a joy in 2016 to see him installed into his new cathedra in Leicester Cathedral."
He studied at Sheffield University and then trained for the ministry at Wycliffe Hall, Oxford.
Since 2013 he has been Suffragan Bishop of Tewkesbury.
He is married to Dr Lynn Snow, a paediatrician and they have 3 children (aged 14, 12 and 10).
Alongside his enjoyment of travel and engaging with other cultures, his interests include sport, music and kayaking.
Bishop Rachel Treweek of Gloucester said: "I have deeply appreciated Bishop Martyn's friendship, support and collegiality.
"Whilst I am sad that Bishop Martyn will be leaving us so early on in my ministry here, I am convinced that today's announcement marks a very natural and appropriate step for him.
"Bishop Martyn's gifts and experience will be richly used in Leicester."