"Today we have finally concluded the 'Contract for the Government of Change'. I'm very happy," said Five Star leader Luigi Di Maio in a Facebook post hailing the development as "an historic moment".
"These have been 70 very intense days... in the end we've managed to achieve what we announced in the electoral compaign."
The 58-page programme contains no mention of a unilateral exit from the eurozone – mooted in previous versions leaked to media – but rejects post-financial crisis austerity policies and features hardline immigration and security proposals.
"The government's actions will target a programme of public debt reduction not through revenue based on taxes and austerity, policies that have not achieved their goal, but rather through increased GDP by the revival of internal demand," the document reads.
It retains controversial proposals to drop sanctions on Russia and review Italy's law on vaccines, which makes at least ten immunizations compulsory for schoolchildren.
The contract promises a version of the League's flat tax with just two tax brackets, 15 and 20 percent, while dropping the anti-immigration party's requirement that all religious sermons be delivered in Italian.
The joint programme will be put to Five Star members, who will vote on the contents of the document via the party's "Rousseau" website which is used for major decisions. It will also be put to a vote by League members.
If approved, the programme will then be presented to Italian President Sergio Mattarella.
On Thursday evening, League leader Matteo Salvini said it would be handed to Mattarella on Monday, by which time he and Di Maio should also have their candidate for prime minister. Mattarella must agree to the parties' nominee before they can seek parliament's approval.
"I am very confident, we have created the basis for the government and the name of the prime minister will not be a problem," Di Maio told supporters late Thursday in the northern town of Monza.