The swearing-in ceremony was delayed by a day after an announcement by the incoming education minister that he had the coronavirus.
With Poland battling a sharp rise in COVID-19 infections, the Cabinet was sworn in in the gardens of the presidential palace in Warsaw rather than indoors.
In the new-look government the number of ministries has been slashed from 20 to 14, with some disappearing and their responsibilities reassigned to other departments.
In a key change, Jarosław Kaczyński, the leader of the governing Law and Justice party, becomes a deputy prime minister.
Kaczyński, who is not the premier despite leading the biggest party in government, is expected to take on a new role as the head of a committee overseeing the key justice, defence and interior ministries.
In another change, Jarosław Gowin, the leader of the Porozumienie (Agreement) grouping – a junior partner in Poland’s ruling coalition – returns to government as the head of the ministry of development, labour and technology, with the rank of deputy prime minister.
The new Cabinet includes Grzegorz Puda as minister of agriculture and rural development.
Absent from Tuesday’s swearing-in ceremony was Przemysław Czarnek, who is set to take over as the minister of education and science.
Czarnek on Monday morning confirmed he had COVID-19, scuppering plans to hold the swearing-in ceremony later the same day.
Four senior politicians who have been in contact with him in recent days have been told to put themselves in quarantine.
Prime Minister Mateusz Morawiecki at the end of last month unveiled a new, pared-back Cabinet after a deal to end a political crisis which one point threatened to tear apart the country’s conservative governing coalition.
The United Right coalition headed by the Law and Justice party has governed Poland since winning a landslide in a 2015 parliamentary election. It secured a second term in power in a parliamentary ballot last October.