Centred at Mount Hermon Aramana, Kozhikode, Malabar is noted for the Attappadi Mission, its de-addiction and dialysis ministries, and for Metropolitan Thomas Mar Timotheos, later Baselios Marthoma Didymus I.
The early leadership of the diocese was provided by H.G. Paulose Mar Severios and H.G. Pathrose Mar Osthathios, who jointly administered it from 1953 to 1968. On 11 November 1966, H.G. Thomas Mar Timotheos became diocesan Metropolitan; he later served the whole Church as His Holiness Baselios Marthoma Didymus I, Catholicos of the East. The diocese continued to grow under later leaders such as Yuhanon Mar Philoxenos from 1995, with its see at Mount Hermon Aramana, Kozhikode.
It is distinguished by humanitarian, spiritual and missionary work, including the Attappadi St. Thomas Mission for Adivasi communities, the Krupa De-addiction Centre at Erumamunda, the St. George Charitable Dialysis Centre at Engapuzha, and its journal, Hermon Sandhesam, published since 1997. It is presently led by H.G. Geevarghese Mar Pachomios.
6 districts, listed alphabetically.