The 67-year-old replaces outgoing Prime Minister Fumio Kishida. Ishiba is seeking to unify the ruling party ahead of elections later this month.
Japan’s parliament on Tuesday formally elected Shigeru Ishiba, the head of the governing Liberal Democratic Party (LDP), as the country’s next prime minister.
The vote came after outgoing Prime Minister Fumio Kishida stepped down.
Ishiba is expected to unveil his cabinet later in the day. The Emperor of Japan will then officially appoint Ishiba and his cabinet in a ceremony at the Imperial Palace.
Snap elections on October 27
Ishiba won a tough race to become the leader of the ruling LDP last week after several previous failed attempts.
The outgoing Prime Minister Kishida announced in August that he would not stand for reelection as the head of the party, suffering from low popularity in Japan.
On Monday, Ishiba announced plans to call for a snap election on October 27, a year before the scheduled date.
“I believe it is important to have the new administration get the public’s judgment as soon as possible,” he said.
The LDP’s popularity has been falling, but the party has managed to stay in power partly due to a weak opposition.
Local media said former chief cabinet secretary Katsunobu Kato will likely be named the finance minister, and Gen Nakatani and Takeshi Iwaya will be named as defense and foreign ministers respectively.
As the new leader of Japan, Ishiba, 67, already has a lot on his plate, such as restoring his party’s popularity, a slowing economy and tackling fears of Chinese aggression.
He supports the creation of a regional military alliance along the lines of NATO.