Anyanwu’s political career began in 1983 when he was the Secretary of the Imo State Youth Organisation (IYO), as well as a political leader in the Democratic Party of Nigeria (DPN) and later, a political leader in United Nigeria Congress Party (UNCP). 

He rose up the rank quickly, and in 2003, he became the Transition Committee Chairman of Ikeduru Local  Government Area, under the People’s Democratic Party. Between 2003 and 2004, he also served as the Secretary of the Imo State Chapter of the Association of Local Government of Nigeria (ALGON).

In 2004, Anyanwu became popular when he was elected as the Chairman of the Ikeduru LGA, Imo State –  a position he held until 2007. Following this, Anyanwu was elected to represent his local government in the Imo State House of Assembly, on the platform of PDP.  He served in this capacity for two tenures (between 2007 and 2015).

During his time as a state legislator, Anyanwu was the Chairman of House Committees on Public Accounts, Finance, and Commerce & Industry. He was also the Vice Chairman of the House Committee on Ethics, Petitions and Privileges.

In 2015, Anyanwu contested for the senatorial seat representing Imo East in the National Assembly. He won the elections under the banner of PDP. In the 8th National Assembly, Anyanwu was the Chairman of the Senate Committee on Ethics, Privileges and Public Petitions; Vice Chairman, Senate Committee on Banking, Insurance and other Financial Institutions; Vice Chairman, Senate Committee on Customs, Excise and Tariffs; Vice Chairman, Senate Committee on Marine Transport. 

Anyanwu declared to run for Governor of Imo State, in the 2019 elections, but he lost the PDP ticket to Emeka Ihedioha.

In 2021, he emerged as the consensus candidate of the South East Zone for the National Secretary of the People’s Democratic Party.