She graduated from the Department of Human Ecology of the Eötvös Loránd University (ELTE) between 1990 and 1992, and also earned a degree in political science in Pécs in 2001.

She became a founding member of its legal successor, the Hungarian Socialist Party (MSZP) on 15 November 1989, and participated in the establishment of its local branch in Pécs.

She ran as a candidate in the 1990 parliamentary election in Pécs (Constituency II, Baranya County), and finished third in the second round, while András Pap (MDF) obtained the mandate.

[1] She was also nominated individual candidate in Pécs (Constituency II), but her name also appeared at the first place on the regional county list of MSZP during the 1994 parliamentary election.

The junior coalition party, the Alliance of Free Democrats (SZDSZ), however, had long emphasized that it would not vote for a partisan President.

Szili as a high-ranking member of the Socialist party was considered partisan, the SZDSZ abstained, enabling the more neutral candidate Sólyom (who was originally nominated by a non-governmental organization Védegylet and later supported by the opposition), to win the office.

Another reason for the failed nomination was that SZDSZ was not consulted ahead of time and Szili lacked qualifications compared to Sólyom who previously held high office as the president of the Constitutional Court of Hungary.

Szili was elected to the Parliament of Hungary via the Baranya County Party list where she was chairperson of the local MSZP branch.

Following the 2014 national election, Szili gradually switched to Fidesz,[12] and became a vocational supporter of Prime Minister Viktor Orbán, who retained his two-third majority in the Hungarian parliament.

Her task covers "coordination tasks related to the aspirations of autonomy in the Carpathian Basin and the concepts of autonomy of social, political and non-governmental organizations, in cooperation with the State Secretariat for National Policy of the Prime Minister's Office, and liaison with European Union and international organizations.

"[13] She voted "no" in the 2016 migrant quota referendum, because she "supports the long-term protection of the entire European Judeo-Christian cultural community".

[17] In order to remain a member of the board of trustees of the University of Pécs, she resigned as Prime Ministerial Commissioner in February 2023.

However, soon, she was appointed chief advisor to the Prime Minister Viktor Orbán, which raised the issue of evasion of conflict of interest legislation.

[18] She joined the Christian Democratic People's Party (KDNP), the coalition partner of the ruling Fidesz, on 31 March 2023.