Defense Minister Ine Eriksen Søreide was named the country's new foreign minister to replace her male colleague Børge Brende, who is stepping down to take over as president of the World Economic Forum.
Søreide, 41, is the first woman to become the top diplomat in NATO member Norway.
She joins Solberg and Finance Minister Siv Jensen in holding "the top three spots" in the right-wing government.
"We're not the first in the world but it is a page in Norway's history that is being written," Solberg said at a press conference.
The Philippines, Switzerland and Liberia have already had such a constellation, she noted.
Back in 1986, the Labour government of female prime minister Gro Harlem Brundtland had almost as many women cabinet members as men, with eight out of 18.
Solberg also announced that Frank Bakke-Jensen would be taking over as defense minister, while his European affairs portfolio would be handed to newcomer Marit Berger Røsland -- a woman.
In power since 2013, the right-wing won a narrow victory in legislative elections on September 11th.
Solberg could announce another government reshuffle by the end of the year if the small centre-right Liberal Party joins the minority coalition, currently made up of Solberg's Conservatives and Jensen's anti-immigration Progress Party.