The Diocese of Lacedaemon (Greek: Μητρόπολις Λακεδαίμονος or Λακεδαιμονίας) was a Christian ecclesiastical province in Laconia, Greece. Extant from at least the middle of the 5th century, it became a metropolis in 1083. During the period of Frankish rule, between ca. 1209 and 1278, it was held by Roman Catholic prelates, and remains a (vacant) titular see of the Catholic Church. The Greek Orthodox see was restored with the Byzantine reconquest in the 1270s, and continued until the see's abolition in 1852.
Christianity came to Laconia and its capital, Sparta, in the 1st century AD, with the first church mentioned in Sparta in ca. 150 AD. Like the rest of the Peloponnese, the Christian community of Sparta was under the jurisdiction of the See of Corinth. A certain Hosios is the first bishop of Sparta attested, in 458; the see was called Lacedaemon , which was the common name for both Sparta and its surrounding region in Byzantine times.
The Chronicle of Monemvasia claims that the inhabitants of Sparta left their city for Sicily due to the Slavic invasions of the late 6th century, and that it was not until the early years of the 9th century that Emperor Nikephoros I (reigned 802–811) rebuilt the city and resettled it with Greek and Armenians settlers. Nevertheless, in the Sixth Ecumenical Council of 681, a Theodosios, "bishop of the city of the Lacedaemonians", participated, and a bishopric of "Lakedeon" is attested in a Notitia Episcopatuum of ca. 800.