Lojze Peterle was born to a peasant family in the Lower Carniolan village of Čužnja Vas near Trebnje.

During his student years, he started collaborating with the Christian left intellectual circle around the journal Revija 2000.

Peterle became prime minister of Slovenia in May 1990 after parliamentary elections of April 1990 won by the DEMOS coalition (which included Christian Democrats and was created in the opposition to the Communist rule).

In 1991, the DEMOS-led Slovene Parliament declared the country's independence from Yugoslavia, in compliance with the result of a referendum held in December the previous year.

Between 1996 and 2000, the Christian Democrats remained in opposition, and Peterle's leadership was frequently challenged by different fractions within the party.

In March 2006, he was elected as Vice President of the European People's Party for a three-year term after recovering from cancer in April 2003.

In September 2016, Peterle joined more than 50 MEPs from six different political groups – including Christofer Fjellner, Ashley Fox, Vicky Ford and Beatrix von Storch – in signing a proposal for a two-term limit of the President of the European Parliament.

This move was widely seen as an effort to prevent incumbent Martin Schulz from holding onto the presidency for a third consecutive term.