Maigh Seóla (), also known as Hy Briuin Seola, was the territory that included land along the east shore of Lough Corrib in County Galway, Ireland. It was bounded to the east by the UàMaine vassal kingdom of Soghain, extending roughly from Lough Corrib east to Knockma Hill and from Clarinbridge north to the County Mayo border. Its rulers belonged to the UàBriúin Seóla and are sometimes found in the annals under the title "King of UàBriúin" and "King of South Connacht". The earliest identifiable kings belonged to the line that became the Clann Cosgraigh. However, in later times the line which would become the Muintir Murchada, under the O'Flaherty chiefs, monopolized the kingship.
The Muintir Murchada were based at Loch Cime (later called Lough Hackett) until forced west of Lough Corrib during the de Burgo led English invasion of Connacht in the 13th century. According to the 17th-century historian RuaidhrààFlaithbheartaigh, Maigh Seóla was considered part of Iar Connacht prior to the 13th-century Anglo-Norman invasion of Connacht. After the de Burgo / Burke family became established in Maigh Seola the territorial term was only used to denote the territory of the O'Flahertys west of Lough Corrib and Lough Mask.
In English, the plain of Maigh Seóla is also known as Moyola.
From the Annals of the Four Masters: