Following the sudden death of President Bingu wa Mutharika in April 2012, he led a delegation of fellow cabinet ministers and Democratic Progressive Party members who sided with his successor, Joyce Banda. He went on to obtain a diploma in Business Management. Upon completion, he subsequently established a number of businesses within Malawi upon where in built a network of wealthy business partners who he would later on persuade to become major donors to the Democratic Progressive Party.
In 2005 he was in turn Deputy Minister of Mines, Natural Resources and Environment, Deputy Minister of Transport and Public works and Minister of irrigation and Water Development.
He held this last position from September 2005 until March 2009. Mia was reelected in the May 2009 general elections on the Democratic Progressive Party ticket.
In the cabinet that became effective on 15 June 2009, he was appointed Minister of National Defense. After the cabinet reshuffle of 9 August 2010, he became Minister of Transport and Public Infrastructure.
This followed the constitutional crisis in which the National Governing Council of the Democratic Progress Party, of which Mia was a senior member, had resolved to contend to the Supreme Court that Joyce Banda was ineligible to succeed Mutharika as President.
In January 2014 Sidik Mia resigned from the People"s Party (Partido Popular (Popular Party)) and from his cabinet post as Minister for Transport. He was expected to join the Malawi Congress Party and become the presidential running mate to its leader, Lazarus Chakwera.
Sidik Mia was elected a Member of Parliament for the Nkombezi constituency in May 2004 in the Chikwawa District and was appointed Deputy Minister of Agriculture, Irrigation and Food Security in June 2004.