Bello Hayatu Gwarzo was elected as senator in the 4th (1999–2003) and 5th (2003–2007) National Assemblies representing Kano North Senatorial District. In April 2007 he ran again but was defeated by Aminu Sule Garo of the All Nigeria Peoples Party (ANPP). In December of that year, Garo's election was annulled on the grounds that he had faked his educational qualifications and Hayatu took his place. Senator Gwarzo was made a member of senate committees on Police Affairs, Millennium Development Goals and Appropriation.
At the Kano PDP congress in August 2009, Senator Gwarzo showed his support for the ex-governor Rabiu Kwankwaso, whose slate won complete control of the state party in a context against nominees of ex-governor Abubakar Rimi.
Gwarzo again ran for reelection as Senator for Kano North on the PDP platform in April 2011, and was again elected, winning 204,905 votes.