Addai-Nimoh is a member of the New Patriotic Party. In 2012, he contested for the Mampong seat on the ticket of the NPP in the 2012 Ghanaian general elections and won. He also served as a Member of parliament for Mampong between 2008 and 2016. He contested in the NPP's presidential primaries in 2014. He lost the bid to represent the party in 2015 parliamentary primaries. In the Annual National Delegates Conference 2022, Mr Nimoh predicted surprises of seeing new faces in the leadership of the NPP. He has in recent times joined the race for the NPP flagbearership for the 2024 elections. He, however, lost the election, coming in 4th out of four contestants.