Baldwin agreed to a five-year deal, sources told ESPN.
"We are proud to have Patrick join the UW-Milwaukee family," chancellor Mark Mone said in a statement. "His deep commitment to have our student-athletes succeed in the classroom as well as on the court reflects the values of Milwaukee basketball. I know he will also play an important role in helping to connect our university to the community."
Baldwin, a former standout player at Northwestern, has been an assistant with the Wildcats for five seasons. He also spent time as an assistant coach at Missouri State, Loyola Chicago and Wisconsin-Green Bay.
"Pat has played an integral role in the building of our program at Northwestern over the last four years," Northwestern coach Chris Collins said in the statement. "He has been heavily involved in all aspects of the program, whether it be on the court as a coach, in recruiting, in the community or with our alumni. He is more than ready to head to Milwaukee and do a terrific job. I know that he will do great things."
Baldwin replaces LaVall Jordan, who left after one season for the head-coaching position at Butler.
"I am extremely excited about this opportunity to lead a program that has a great tradition of winning, resources to help facilitate our ascension in the Horizon League and commitment from the entire administration," Baldwin said in the statement. "Our main goal and focus is to compete and win championships. I can't wait to get started with our current roster of student-athletes and work toward achieving great success both on and off the court."