Sanae Takaichi has been elected as Japan's first female prime minister, securing 237 votes in the 465-seat lower house.
Her appointment followed a coalition agreement between her ruling Liberal Democratic Party and the right-wing Japan Innovation Party, and she was sworn in on Tuesday.
Ms Takaichi's victory signifies a notable shift towards more conservative policies on issues such as immigration and social matters.
The election prompted a positive economic response, with Japan's stock market hitting a record high and the yen weakening, benefiting exporters.
Coming from the same hardline LDP faction as Shinzo Abe, Ms Takaichi is expected to pursue similar stimulus measures and has stressed the importance of political stability for economic strength and diplomacy.