The 30-year-old Chicago-born singer-actress, who has lost 80lb (36kg) and is a WeightWatchers spokeswoman, will open the Jennifer Hudson WeightWatchers Centre today.
Chicago Mayor Rahm Emanuel is due to attend the event in the city's Hyde Park neighbourhood on the South Side.
WeightWatchers will donate part of the centre's revenue to a foundation in honour of the Dreamgirls star's late nephew Julian King.
In 2008, Hudson's mother and brother were found dead in the family's home – and King's body was found days later in an abandoned car. All three had been shot.