Mark was elected to his position as President of the Senate of Nigeria on June 6, 2007. In April 2012, Mark expressed concern for the new wave of terrorism from an Islamic sect that was taking hold on Nigeria; he said that it was turning Nigeria into a laughing stock and that the actions are "inhuman and [do] not enjoy the support of any right-thinking member of the society." Mark has been actively pleading with Boko Haram, hoping that they will open up a dialogue with the government in the interest of peace. Mark was criticized for claiming that telephone was not meant for ordinary people while he was Minister of Communication.
David Mark ran for re-election to the Senate for Benue South in April 2011 and was elected for a fourth term. Some exit polls suggested that Mark would not win, making his victory the subject of some scrutiny. Mark noted that the INEC polls pointed to a decisive victory, and called for his opponents to work together to improve Nigeria.
When leading the review of the Constitution, Mark reportedly urged his colleagues to set their personal interests and focus on the interests of the Nigerian people. After the UK criticized Nigeria's Prohibition of Same-Sex Marriage bill, threatening to pull their foreign aid, Mark responded that they "should keep [their] aid." Mark called Nigeria's National Football Federation the "centre of corruption in the country", suggesting that they may need to temporarily disband to allow for reconstruction.