This is the first official statement by the King after several hours of silence ordered by the kingdom’s security service.
Hamzah was accused of a plot to destabilize the country, and as part of the operations, at least 16 people were arrested.
Foreign Minister Ayman Safadi pointed out that the plot had ties to foreign parties, although he did not identify them.
Hamzah was named crown prince in 1999 by his father, King Hussein, who ruled Jordan from 1952 until his death in 1999.
In 2004, Abdullah II named his son Hussein first in the royal succession and stripped Hamzah of that title.
Hamzah, the former heir to the throne, used social and traditional media on Saturday to accuse the rulers of corruption and ineptitude in a video message.
However, he retracted on from his statement on Monday and expressed loyalty to King Abdullah II, his half brother by his father, and offered his support for the monarchy.
Hamzah pledged before the Hashemite family to follow in the steps of his parents and grandparents, to be faithful to his message and put Jordan’s interest, Constitution and laws above all considerations.