Robert Mbui is the member of the National Assembly representing Kathiani Constituency and Deputy Leader of Minority in the National Assembly. He holds a Master's in Strategic Management from the Kenya Institute of Management.

Mbui was first elected to Parliament in 2013. Prior to this he had served as the CDF chairman for the larger Kathiani constituency before Mavoko constituency was carved out of it from 2008 to 2011. During his tenure as CDF chair, he initiated many projects to improve the education and health sector. Under his stewardship the constituency fund was voted the best used in the country.His track record and social skills propelled him to the National Assembly where he is currently serving his second term. During the 2017 elections he was one of the best performers countrywide, garnering 40,000 votes against his closest rival's 1,000 votes.