The economic capital held a "save the Expo" summit following the arrests last week of eight people accused of bid rigging, awarding contracts without invitation to tender and falsifying documents.
"We have not lost a minute," Milan mayor Giuliano Pisapia told journalists at the end of the emergency meeting, insisting the scandals "have been overcome".
"We're not starting again, we're picking up where we left off and tightening up the project," he said, while Transport Minister Maurizio Lupi said the government "will do everything possible to make sure the deadlines are respected".
The Expo, which will look at the theme "Feeding the Planet, Energy for Life" from economic, scientific and cultural perspectives, will be held from May 1st to October 31st 2015.
The government has pledged to invest €1.5 billion in the project.
Delays in the construction of the immense site in the suburbs of Milan have already drawn criticism.
Italy's new Prime Minister Matteo Renzi is expected to travel to Milan at the start of April to show his support for the project, which the government hopes will mark the beginning of a new era of growth and prosperity in the eurozone's third largest economy, hit hard by a two-year recession.
Some 145 countries have announced they will be taking part in the Expo so far.