A wedding ceremony for Princess Ayako and Kei Moriya, a commoner who works for major shipping firm Nippon Yusen K.K., was held at Meiji Jingu in central Tokyo on Monday.
She will receive about 107 million yen ($950,000) from the state to maintain her dignity after her marriage based on the law on imperial household finance.
Mr Moriya said he had been attracted to her gentle spirit.
Arriving at the shrine in traditional court attire - a kimono robe and hakama trousers - with her hair tied in the osuberakashi ancient style for noblewomen, the princess smiled at Moriya, who had been waiting for her in a morning suit. A small group of family members attended the actual ceremony itself, where rings were exchanged, along with a traditional cup of sake.
Afterwards, the couple spoke to the waiting press. "We want to make efforts to become a couple like my mother and father".
Her groom wore pin-striped pants, a morning jacket, and a silk top hat that once belonged to the bride's father, the late Prince Takamodo, according to CNN.
With the departure of Princess Ayako, the number of imperial family members will fall to 18 and that of female members to 13.
While members of the Japanese imperial family have been able to choose who they marry for three generations, according to Al Jazeera, women who marry commoners must renounce their royal status while male members who do the same are allowed to stay in the family.
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"I'm delighted at this happy occasion", he said.
Ayako said: "It didn't feel as though we had met for the first time", to which Moriya added: "And I knew I wanted to spend the rest of my life with her".
Emperor Akihito has said he will abdicate. Mr Moriya looked cool, as he usually does.
Yasuyuki Goto, 33, a friend of Moriya's, also wished the couple well.
"I am awed by how blessed I am", Ayako said.
Today Princess Ayako was pictured leaving her residence with her mother Princess Hisako of Takamado, 65, in a stunning bridal kimono.
Princess Ayako graduated from Josai International University in Chiba Prefecture and earned a master's degree there in 2016. He enjoys running in marathons and competing in triathlons.