[3] He stayed on in the same university until 1979 for the post-graduate work on his dissertation in Economics which he defended in 1980 receiving the degree of Candidate of Science (roughly Ph.D. equivalent).

[3][6] As minister, Pynzenyk introduced the first economic reforms in the newly independent Ukraine, helping transform the country into a market economy.

Three years later, after the Orange Revolution, Pynzenyk was chosen as the Minister of Economy[8] on February 4, 2005, and served his post until August 2006.

Then on November 3, 2007, he became a deputy of the Verkhovna Rada of the sixth convocation as a member of the Reforms and Order Party, which participated in the elections as part of the Yulia Tymoshenko Bloc.

He offered his resignation on February 12, 2008 because he could not abandon the principles of a balanced budget with a minimum deficit, realistic revenue sources and limits on government borrowing.

The weakest leave their combat posts and turn to other activities", Tymoshenko also stated: "He was in hospital and was not working for health reasons".

[12] Pynzenyk, in conversation with United States Ambassador to Ukraine John F. Tefft at a meeting on February 22, 2010 showed "frustration at his inability to convince Tymosehnko to take advantage of the opportunity presented by the 2008–2009 Ukrainian financial crisis to reform” (according to Tefft) and called Tymoshenko's decisions “normally guided by ‘adventurous populism,’” which she saw as a tool to “consolidate power in her own hands.”[13] On February 17, 2009, the Verkhovna Rada officially dismissed Pynzenyk.

[16] Pynzenyk returned to national politics as number 7 on the party list of UDAR of Vitaliy Klychko for the 2012 Ukrainian parliamentary election.

[19] In the 2014 Ukrainian parliamentary election he was again re-elected into parliament; this time after placing 17th on the electoral list of Petro Poroshenko Bloc.