His Majesty is scheduled to preside over the unveiling at 5.30pm.
The King Rama 8 statue is perched atop a multi-purpose building next to the bridge. The statue is in a standing posture.
The monument was constructed to commemorate King Ananda Mahidol, His Majesty the King's elder brother.
It will remain a permanent fixture on the bridge, which was built on the King's initiative to alleviate traffic and connect Bangkok with the Thon Buri side of the Chao Phraya River.
MR Sukhumbhand said the multi-purpose building commands a sweeping view of the Chao Phraya River and important historical places nearby such as Phra Sumen Fort and Bang Khun Prom Palace.
The area near the statue is expected to become a new recreational spot.
MR Sukhumbhand said the organising committee had already prepared the ground for the royal ceremony.
The Bangkok Metropolitan Administration has arranged the area and facilities to accommodate people participating in the ceremony. A medical team will be on standby and drinking water will be provided during the ceremony.