In the 2007 national elections, Glavak became a member of the Croatian Parliament, representing the HDZ list.

However, she suspended her mandate following her appointment as deputy spokesperson of the government led by Prime Minister Ivo Sanader.

In the 2014 presidential election, she was a staff member of Kolinda Grabar-Kitarović's campaign.

From 2016, she served as spokesperson for the Government of the Republic of Croatia under successive prime ministers Tihomir Orešković and Andrej Plenković.

In 2018, she resigned from this post and returned to the Croatian Parliament, where she replaced Darko Horvat.