The Roman Catholic Diocese of Telšiai (Latin: Telsen(sis)) is a suffragan Latin diocese in the ecclesiastical province of the Metropolitan of Kaunas, one of two in Lithuania.

[1] On 28 May 1997, it lost territory to establish the Diocese of Šiauliai.

On 24 December 1991, the Territorial Prelature of Klaipėda (Memel), which had been seceded from the Diocese of Ermland on 4 April 1926, and was repeatedly held in personal union by the Bishops already, was merged into the Telšiai Diocese.

[2][3] 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.

It also has the former cathedral of the Diocese of Samogitia in Varniai and a minor basilica dedicated to the Visitation of the Blessed Virgin Mary in Žemaičių Kalvarija.