Today, there are roughly between 300,000 and 600,000 Irish-descendants living in Mexico City, and the Northern region of the country, where Irish last names such as Bay, Lamport, Byrne, Walsh, Foley, Hayes, and O'Leary are common, especially in the states of Sonora, Chihuahua, Nuevo Leon, and Durango.

Many Mexican Irish communities existed in Mexican Texas until the Texas Revolution. Many Irish then sided with Catholic Mexico against Protestant pro-U.S. elements.The Batallón de San Patricio was a largely (ethnically) Irish battalion of U.S. troops who deserted and fought alongside the Mexican Army against the United States in the Mexican-American War of 1846 to 1848.In some cases, Irish immigrants or Americans left from California (the Irish Confederate army of Fort Yuma, Arizona during the American Civil War in 1861) and blended into Mexican society instead.

Probably the most famous Irishman ever to reside in Mexico is the Wexfordman William Lamport, better known to most Mexicans as Guillen de Lampart, precursor of the Independence movement and author of the first proclamation of independence in the New World. His statue stands today in the Crypt of Heroes beneath the Column of Independence in Mexico City. Some authorities claim he was the inspiration for Johnston McCulley's Zorro, though the extent to which this may be true is disputed.

Álvaro Obregón (possibly O'Brian) was president of Mexico during 1920-24 and Obregón city and airport are named in his honour. Mexico also has a large number of people of Irish ancestry, among them the actor Anthony Quinn. There are also monuments in Mexico City paying tribute to those Irish who fought for Mexico in the 19th century. There is a monument to Los Patricios in the fort of Churubusco. During the Potato Famine, thousands of Irish immigrants entered the country, today, over 600,000 Irish descendants live in Mexico. Other Mexicans of Irish descent are: Romulo O'Farril, Juan O'Gorman, Edmundo O'Gorman, Anthony Quinn, Alejo Bay (Governor of the state of Sonora), Famed Conductor Felix Carrasco, Guillermo Purcell a businessman, former Miss Mexico Judith Grace Gonzalez, among many others. Today, the Irish community in Mexico is a thriving one and is mainly concentrated in Mexico City and the northern states of Mexico.