Zīle began his political career in 1990, when he became member of the executive institution of the Latvian Citizens' Congress, the Committee of Latvia.

After being a deputy in the Riga City Council, he became an assistant to Ilmārs Dāliņš, a member of the 5th Saeima (Parliament of Latvia).

In August 2011, he resigned his post as co-chairman, declaring that he wishes to focus his attention on the events in the European Parliament and believes that the leaders of the National Alliance should be based in Latvia.

Left-wing British politicians including the Secretary of State for Foreign and Commonwealth Affairs, David Miliband and Denis MacShane criticised the activities and views of Zīle and his party.

[12] In a response, Shadow Foreign Secretary William Hague demanded an apology to TB/LNNK and the Latvian government from Miliband, describing his remarks as recycling "false Soviet propaganda" and noting that "the majority of parties forming Latvia’s current Government including the Prime Minister’s party, have attended the commemoration of Latvians who fought in the Second World War".

He has published articles and research papers on property rights and agricultural policy issues in the United States of America, Australia, Norway, Finland, Hungary, Slovakia and Germany.

[15] Zīle began his political activities as a member of the 18th November Association, Latvian Citizen's Congress and Union "For Fatherland and Freedom".

The objective of the foundation is to offer and introduce new ideas for the political, economic and social life in Latvia and the EU, based on nationally conservative values.

Prior to the 9th Saeima elections Zīle developed an extensive economic reform program (sometimes called Zīle's program), designed to prevent a looming real estate crisis and to create a socially equitable tax system in Latvia, which would be oriented towards productive investments.

[20] In the European Parliament, Zīle's current agenda is focused on issues related to the EU transport policy, especially the "Rail Baltica" railway project; overcoming the economic crisis; the economic governance of the EU and solving banking issues; energy, especially ensuring the energy independence of the Baltic countries from Russia.

In Latvian domestic affairs, Zīle has been continuing activities focused on ensuring the long term macroeconomic stability and overhaul of the tax system.

His objective is to prevent the creation of a new banking and real estate bubble based on non-resident activities, as well as to decrease the tax burden on labour, especially low income households and families with children.

He also advocates tax increase on capital gains and income from speculative activities with real estate, as well as calls for a state aid for the acquisition of residence for new families.