St George's Channel (Welsh: Sianel San Siôr, Irish: Muir Bhreatan) is a sea channel connecting the Irish Sea to the north and the Celtic Sea to the southwest.

Historically, the name "St George's Channel" was used interchangeably with "Irish Sea" or "Irish Channel" to encompass all the waters between Ireland to the west and Great Britain to the east. Later it was restricted to the portion separating Wales from Leinster, sometimes extending south to the waters between the West Country of England and East Munster; the latter have since the 1970s come to be called the Celtic Sea. In Ireland "St George's Channel" is now usually taken to refer only to the narrowest part of the channel, between Carnsore Point in Wexford and St David's Head in Pembrokeshire. However, it remains common in Ireland to talk about a cross-channel trip, cross-channel soccer, etc., where "cross-channel" means "to/from Great Britain".

The current (third, 1953) edition of the International Hydrographic Organization's publication Limits of Oceans and Seas defines the southern limit of "Irish Sea and St. George's Channel" as "A line joining St. David's Head (51°54′N 5°19′W / 51.900°N 5.317°W / 51.900; -5.317) to Carnsore Point (52°10′N 6°22′W / 52.167°N 6.367°W / 52.167; -6.367)"; it does not define the two waterbodies separately. The 2002 draft fourth edition omits the "and St. George's Channel" part of the label.

Saint George was a soldier in the Roman army in the 3rd and 4th centuries AD, venerated as a Christian martyr.

Saint George or Saint George's may also refer to:

Education

Buildings

Places

Australia

Bermuda

Saint-Georges may refer to:

People

Places

In Canada

In France