Łukowski's previous role was as Siewiera's deputy, Polish state news agency PAP reported.
Siewiera stepped down from his position as Duda’s national security advisor last month to pursue a scholarship programme at the University of Oxford, according to reports at the time.
At a ceremony in the presidential palace on Monday, Duda also appointed his long-time aide Wojciech Kolarski as his new top foreign policy aide.
Andrzej Duda and Wojciech Kolarski during the ceremony at the presidential palace in Warsaw on Monday. PAP/Leszek Szymański
Kolarski replaces Mieszko Pawlak as the head of the president's International Policy Bureau, reporters were told.
Pawlak, meanwhile, will now serve as a deputy national security advisor to Duda, the Polish President's Office said.
(gs)
Source: IAR, PAP, TVN24