Mars later made his announcement public through the media stating, "I'm very thankful to the MI audience for joining me in supporting this cause".
Over the past couple of years, controversy has surrounded Flint after the city's water supply was contaminated with lead.
Mars made the announcement to a screaming crowd of fans at his sold out show Saturday night at the Palace of Auburn Hills in MI.
The artist has performed in Europe and recently kicked off the North American leg of the tour in Las Vegas (28Jun17).
All the proceeds from the Detroit show will go directly to The Community Foundation of Greater Flint to help those affected. That decision pumped high concentrations of lead through aging pipes into the water of the homes of mostly poor, black residents and caused an outbreak of Legionnaires disease that has claimed the lives of at least 12 people.
Mars' album "24K Magic" was released in November 2016 and has sold over 2 million copies. The water was improperly treated, leading to elevated levels of lead.
US President Donald Trump commented on a visit to the midwestern state: "It used to be that cars were made in Flint and you couldn't drink the water in Mexico".
As of this post, it's been more than 1,200 days since the residents of Flint, Michigan have been without clean water.