Born in Orzinuovi, Martinazzoli studied at Collegio Borromeo in Pavia, where he received a law degree.

[2] In 1992, when the DC party was being wiped out by the Tangentopoli bribery scandal, Martinazzoli, generally respected as an honest and competent man, was elected national secretary.

In the new majoritarian system, Martinazzoli's party placed itself in the political centre between the political left, which included the heirs of the Italian Communist Party, and the political right with the new Berlusconi's Forza Italia, which had allied with the Northern Italy-based regionalist party, the Lega Nord (Northern League), as part of the Pole of Freedoms, and the post-fascist National Alliance as part of the Pole of Good Government.

His will not to ally with any of them caused numerous politicians, such as Pierferdinando Casini and Clemente Mastella, to leave the PPI and form the Christian Democratic Centre (CCD), which supported Berlusconi.

[2] After the PPI was dissolved in 2002, Martinazzoli migrated to Mastella's UDEUR in 2004, being appointed as its president, a position from which he resigned in 2005.