Kadhimi was rumored to be among the prime ministerial contenders since December, following the previous incumbent’s resignation.
He now has 30 days to form a new cabinet and present it to parliament for approval.
Born in Baghdad in 1967, he has a law degree and has also published several books, including Humanitarian Concerns, which was selected in 2000 by the European Union as the best book written by a political refugee.
He worked as a reporter and, until 2016, wrote widely on the reforms needed in Iraq.
Kadhimi follows two candidates who had been nominated for the role since former prime minister Adel Abdul Mahdi resigned from the post in November.
The first candidate designated to succeed Abdul Mahdi, Mohammed Allawi, withdrew his candidacy on March 1 after the Iraqi parliament refused to approve his cabinet.
The second was Adnan Al Zurfi, who withdrew his candidacy earlier today.