The diocese was established on 4 April 1926 on territory split off from the Diocese of Samogitia.[1] On 28 May 1997, it lost territory to establish the Diocese of Šiauliai.
As of 2014, the diocese pastorally served 564,000 Catholics (80.0% of 705,000 total) on 13,373 square kilometres (5,163 sq mi) in 79 parishes and 95 missions with 164 priests (148 diocesan, 16 religious), 50 lay religious (18 brothers, 32 sisters) and 20 seminarians studying at the Telšiai Bishop Vincentas Borisevičius Priest Seminary.
Apostolic Administrator Bishop Petras Maželis (1959.11.10 – 1964.02.14 see below) while Titular Bishop of Celenderis (1955.05.22 – 1964.02.14) as Auxiliary Bishop of Telšiai (1955.05.22 – 1964.02.14); previously Bishop-Prelate of Territorial Prelature of Klaipėda (Lithuania) (1949.12.20 – 1955.05.22)
Petras Maželis (see above 1964.02.14 – death 1966.05.21), also again Bishop-Prelate of Klaipėda (1964.02.14 – 1966.05.21)
Apostolic Administrator Bishop Juozapas Pletkus (1967.11.08 – death 1975.09.29) while Titular Bishop of Tubia (1967.11.08 – 1975.09.29), also Apostolic Administrator of Klaipėda (Lithuania) (1967.11.08 – 1975.09.29)
Apostolic Administrator Bishop Antanas Vaičius (1982.07.05 – 1989.03.10 see below), Titular Bishop of Sullectum (1982.07.05 – 1989.03.10) and Apostolic Administrator of Klaipėda (Lithuania) (1982.07.05 – 1991.12.24)
Antanas Vaičius (see above 1989.03.10 – retired 2001.05.26), died 2008
Jonas Algimantas Boruta, SJ (2002.01.05 – 2017.09.18), previously Titular Bishop of Vulturara (1997.05.28 – 2002.01.05) as Auxiliary Bishop of Archdiocese of Vilnius (Lithuania) (1997.05.28 – 2002.01.05)
Kęstutis Kėvalas (2017.09.18 – 2020.02.19),[4] previously Titular Bishop of Abziri (2012.09.27 – 2017.04.20) as Auxiliary Bishop of Kaunas (Lithuania) (2012.09.27 – 2017.04.20), coadjutor bishop of Telšiai (2017.04.20 – 2017.09.18); later promoted as Archbishop of Kaunas (2020.02.19-).
Algirdas Jurevičius (2020.06.01-),[4] previously Titular Bishop of Materiana and Auxiliary Bishop of Kaunas (2018.07.02-2020.06.01)
Auxiliary episcopate
Linas Vodopjanovas (Genadijus), OFM (2012.02.11 – 2016.05.20), appointed as Bishop of Panevėžys