Princess Ayako, the youngest child of Princess Hisako and the late Prince Takamodo, cousin of Emperor Akihito, chose to wed a shipping company worker Kei Moriya.
The ceremony took place in at the Meiji Shrine in Tokyo on Monday, where onlookers saw the princess tie the knot with the 32-year-old commoner.
The 28-year-old daughter of Emperor Akihito's late cousin will reportedly receive a lump sum payment of $1.3 million from the state after wedding Kei Moriya.
The money is meant to help the princess maintain her high standard of living after surrendering her royal status, as decided by a government council earlier this month.
While female members of the Japanese royal family must forfeit their status when marrying a commoner, the same rule does not apply to their male counterparts.