The surname of Walsh as an Irish wilisc surname which means foreign Welsh. term Breathnach in Irish referred to ‘Briton’ or ’Breton’ which meant "foreigner" or literally "Welshman". It was used to denote the Welshmen who arrived in Ireland after the Anglo-Norman invasion of 1170.

In Old High German the term walh changed to walch.

In Ireland the Walsh surname is located in the counties of Kilkenny and Mayo. It is the fourth most popular surname in all of Ireland.

Various forms of the name are "Walshe", "Welsh", "Brannagh" and "Breathnach."
The places of origin for the Walsh surname are Ireland and England.

In England the Walsh families are generally in Lancashire county. In Scotland the Walsh name is frequent in the county of Lanarkshire. The states of New York and Massachusetts have higher numbers of people with the Walsh surname.

Walsh families worked as farmers during the 1880s.

Famous: Chris Lee Walsh (professional football player with the Minnesota Vikings), Ed Walsh (early 20th century baseball player with Chicago White Sox and Boston Braves as a pitcher), John E. Walsh (head of TV’s America's Most Wanted and anti-crime advocate), Matt Walsh (professional comedian), Pat Walsh (New Zealand rugby union footballer), Maria E. Walsh (Argentine singer and writer), Kerry Walsh (American beach volleyball player, gold medalists in 2004 and 2008 Olympics), Ian Walsh (a Welsh international footballer), Frances Walsh (screenwriter, film producer, and musician), Evalyn Walsh (19th century mining heiress, purchased the 45-carat Hope Diamond in 1911 for $118,000, became the last private owner of the Hope Diamond) and John Walsh (19th century developer of a large department store in England).