Prior to the political career he was an advertising, media, and public relations executive. Following his nomination he co-authored a law which allowed the government to block websites that it sees harmful for children. He also co-authored a law which would force internationally funded non-profit organizations to register as "foreign agants".
In May of the same year Zheleznyak suggest the Duma to pass a bill that would make criticism of the World War II coalition member states' illegal and will be punished by imprisonment for up to 3 years. In June 2013 he told Economics and Life online journal that
The US, which presents itself as a bastion of democracy, has in fact been carrying out minute-by-minute surveillance of tens of millions of citizens of Russia and other countries. Following this remark which was in reference to Edward Snowden's leak, he referred to anti-gay law in Russia that it is an American reproach of sticking their noses into the personal correspondence of tens of millions of Russian citizens.
As a result of the 2014 Crimean crisis, the federal government of the United States under Barack Obama blacklisted Sergei Zheleznyak.