In 1990 he founded the Sodalitas non-profit organization, which in Bellaria-Igea Marina has a series of residences and summer camps.

In 1996 he opened the Mantovani Foundation, specialized in the construction and management of nursing homes for the elderly.

With the first he builds social welfare residences and with the second he manages four RSAs in the province of Milan which, added to those led by Sodalitas, make eleven structures and 830 beds, all accredited in the Lombardy region rankings.

In November 2008, the municipal councilors that supported Mantovani resigned to allow him to reapply for the third consecutive time for mayor.

From 29 January 2011 he became the new regional coordinator of The People of Freedom in Lombardy, succeeding the resigning Guido Podestà, president of the Province of Milan.

On 13 October 2015, he was arrested in Milan, accused of corruption, bid-rigging, and misdirection of public funds for school construction and patients needing dialysis transport, between 2012 and 2014, while Vice President of Lombardy.