Reverend Claude-Jean Allouez celebrated Mass with a Native American tribe near present-day Oconto in December 1669, the feast of St. Francis Xavier.

The missionaries worked with the Fox, Sauk, and Winnebago tribes, protected by Fort Francis near Green Bay.

In 1837, the missionary Reverend Florimund J. Bonduel traveled from Green Bay to visit the French fur trader Solomon Juneau in Milwaukee.

[9] Designed by architect Victor Schulte in the Zopfstil style, St. Mary's was built to serve German immigrants.

The Annunciation altarpiece in St. Mary's, painted by Franz Xavier Glink was donated to the diocese by King Ludwig I of Bavaria.

In 1880, Bishop Michael Heiss of La Crosse was appointed coadjutor archbishop of Milwaukee by Pope Leo XIII to assist Henni.

In 1889, the Wisconsin Legislature passed the Bennett Law which required all primary and secondary schools in the state to teach major subjects in English.

The law was bitterly resented by German-American communities, both Catholic and Lutheran, that ran schools teaching in German.

At the beginning of Katzer's tenure in 1891, the archdiocese contained 227 priests, 268 churches, and 125 parochial schools to serve a Catholics population of 180,000.

A prominent Irish newspaper, the Catholic Citizen, labeled the Bennett Law a convergence of "all the sectarian, bigoted, fanatical and crazy impurities" within the Republican Party which had taken the reins of power.

Following Messmer's death in 1930, Pope Pius XI that same year named Bishop Samuel Stritch from the Diocese of Toledo as fifth archbishop of Milwaukee.

[22] An opponent of the controversial Charles Coughlin, he once wrote a letter to a Milwaukee rabbi in which he rebuked those who "gain and hold a popular audience, degrade themselves and abuse the trust reposed in them by misquoting, half-quoting, and actually insinuating half-truths.

Pope Pius XII in 1940 appointed Bishop Moses E. Kiley of the Diocese of Trenton as the next archbishop of Milwaukee.

In 1967, Cousins expressed his support for open housing and Groppi's other objectives, triggering a backlash from some Catholics in the archdiocese.

In 1977, Pope Paul VI appointed Reverend Rembert Weakland, abbot primate of the Benedictine Confederation, as archbishop of Milwaukee.

Amidst abortion controversies, Weakland participated in public "listening sessions", encouraging Catholic women to share their views on the issue.

While Weakland was waiting for his resignation to be accepted, the news media in May 2002 reported that the archdiocese had paid a $450,000 settlement in 1998 to Paul Marcoux, a former seminarian.

The next archbishop of Milwaukee was Auxiliary Bishop Timothy M. Dolan of St. Louis, named by John Paul II in 2001.

To replace Dolan, Pope Benedict XVI named Bishop Jerome E. Listecki of La Crosse in 2009.

The archdiocese filed for Chapter 11 bankruptcy protection in January 2011 after it failed to reach a settlement with two dozen victims of sexual abuse by Catholic clergy.

"[37] In March 2023, Listecki removed the right to hear confession and give absolution from Reverend James Connell, a retired archdiocesan priest.

In an opinion article in USA Today, Connell had expressed support for a proposed Delaware law that would invalidate the clergy-penitent privilege in cases that involved sexual abuse.

A 2003 report released by the Wisconsin Senate listed 58 priests from the Archdiocese of Milwaukee with credible accusations of sexual abuse of children.

[39] In the report, Archbishop Weakland admitted allowing priests guilty of child sex abuse to continue in ministry without warning parishioners or alerting the police.

[41] In July 2011, the archdiocese launched "a national advertising campaign to notify sex abuse victims of their deadline to file claims.

[45][46] The archdiocese in June 2021 announced that it would only cooperate with an investigation by Wisconsin Attorney General Josh Kaul as far as sexual abuse allegations against living priests.