Sheikh Abdullah bin Nasser Al Thani, who has been at the interior ministry since 2005, is regarded as a longstanding ally of the new emir, Sheikh Tamim bin Hamad Al Thani.
A former special forces soldier, the new prime minister takes on the challenge of replacing the towering presence of the previous premier, nicknamed HBJ, who also holds the post of foreign minister.
Alongside the former emir, HBJ helped turn the strategic Gulf state into a global investor and leading regional diplomatic force.
It is still unclear whether HBJ will continue to manage the country’s aggressive Qatar Investment Authority, which manages assets of more than $100bn.
Chairman of Qatar’s antiterrorism committee, Sheikh Abdullah has also served under the new emir on the board of the state’s communications and information technology regulator.
Sheikh Tamim, educated at UK military college Sandhurst, began his career in the military and has held security-related posts during his decade of grooming for the top job of this strategic US ally.
The new emir, who took power when his father Sheikh Hamad bin Khalifa abdicated on Tuesday, is scheduled to speak to the nation at 1800 local time (1500 GMT) on Wednesday.
A broad cabinet reshuffle, in which younger politicians are expected to be appointed, is also expected on Wednesday.
Sheikh Tamim is expected to appoint new names to key positions such as foreign affairs and finance.