The government made the decision that prompts the general election on Thursday morning and asked the emperor to approve it.
"On the basis of Article 7 of the basic law, the lower house is dissolved," the order read.
Later in the day, the cabinet will formally set the date for the new election — the first in four years, according to the NHK broadcaster. It marked the shortest period between a new prime minister taking office and the dissolution of the lower house in postwar Japan.
Earlier in October, Japan's newly appointed prime minister, Fumio Kishida, announced his decision to dissolve the country's lower house on 14 October and schedule the next general election for 31 October, with the election campaign beginning on 19 October. The lower house's mandate was set to expire next week.