In 2014, Rónai was elected as a member of the Pest County Municipality. He was a founding member of the Democratic Coalition and became its spokesperson in 2018.[4] He was nominated in third place on the Democratic Coalition's European Parliament list and elected as MEP in the 2019 election.[5][3]
Since 2022, Rónai has been vice-chair of the Committee of Inquiry to investigate the use of Pegasus and equivalent surveillance spyware.[6] He is a member of the Committee on Budgetary Control, the Committee on the Environment, Public Health and Food Safety, and the Delegation for relations with the NATO Parliamentary Assembly.[7] In addition to his committee assignments, he is part of the European Parliament Intergroup on Climate Change, Biodiversity and Sustainable Development.[8]