[5] In May 2017, Petříček was appointed political deputy minister of labor and social affairs of the Czech Republic Michaela Marksová in the Cabinet of Bohuslav Sobotka.

He actively supported Petr Dolínek against Miloslav Ludvík in deciding on the position of the leading ČSSD candidate for the 2017 Czech legislative election.

[10] At the end of 2018, Petříček met Chinese Minister of Foreign Affairs Wang Yi to discuss intergovernmental commission that would improve China-Czech Republic relations.

[13] Petříček criticised the Assassination of Jamal Khashoggi, wanting a stronger EU stance on the event at the Council of Foreign Ministers.

[14] In November 2018, Petříček went on a two-day visit to Israel and spread criticism regarding the Israeli annexation on East Jerusalem, which Palestinians claimed as the capital of the State of Palestine.