The agreement was signed on Monday at President-elect Uhuru Kenyatta’s residence in Nairobi.
With UDF joining the alliance, Jubilee will boost its majority in the National Assembly and Senate.
UDF will strengthen Jubilee’s numerical strength in Parliament to 216 members.
UDF Chairman Hassan Osman said: “The agreement entails an undertaking that both parties will execute the joint programs of the parties as contained in their manifestos and that we they will work together to ensure that the government agenda is pushed forward.”
Jubilee has been wooing Mudavadi to enter into a post-election agreement since Kenyatta was declared winner of the March 4 presidential poll.
The Jubilee coalition which is composed of four parties – The National Alliance party, United Republican Party, Narc and Republican Congress – has in recent weeks entered into several agreement s with other parties.
Towards the end of March the coalition deposited five post election coalition agreements with the Registrar of Political Parties.
The agreements are with New Ford Kenya, Ford People, Alliance Party of Kenya, Chama Cha Uzalendo and People’s Democratic Party.
According to the Political Parties Act, any pre or post-elections deals must be deposited with the Registrar of Political Parties.
The Jubilee coalition has also signed an agreement with Burundi’s ruling party in a bid to strengthen regional ties.
The coalition said it was looking forward to working with the East African region’s ruling parties in a bid to foster regional integration and is in the process of signing another agreement with Tanzanian ruling party Chama Cha Mapinduzi.