The government had accused Prince Hamzah of involvement in a conspiracy to â€˜destabiliseâ€™ the kingdomâ€™s security.
Jordanâ€™s King Abdullah II and his half-brother Prince Hamzah bin Al Hussein have made their first joint public appearance since a palace feud last week.
On Sunday, members of the Jordanian royal family marked the centenary of the establishment of the Emirate of Transjordan, a British protectorate that preceded the kingdom.
The royal palace released a photo with Abdullah II, Prince Hamzah, Crown Prince Al Hussein bin Abdullah II and other dignitaries at the grave of King Talal in Amman, Jordanâ€™s capital.
Hamzah, the former crown prince, was seen for the first time since he was placed under a form of house arrest amid accusations he was involved in a plot to destabilise the kingdom.
The king and the prince had a rare public rift last week, with Abdullah II portraying it as an act of sedition involving his half-brother and two other senior officials. Hamzah denied the allegations.
At least 18 other people were detained in connection with the plot.
But Abdullah said on Wednesday that Hamzah, who has signed a letter pledging his loyalty to the king following mediation by an uncle, was safe in his palace under his â€œcareâ€.
In an address read out in his name on state television, the king added that â€œsedition has been nipped in the budâ€.
Abdullah and Hamzah are sons of the late King Al Hussein bin Talal, who ruled for almost half a century until his death in 1999.
Hamzah had been appointed crown prince and heir to the throne in 1999 in line with his fatherâ€™s wishes, but Abdullah stripped him of the title in 2004 and named his eldest son Hussein in Hamzahâ€™s place.
Hamzah, in a video message published by the BBC on April 3, claimed he had been placed under house arrest and accused Jordanâ€™s rulers of corruption and ineptitude.
Foreign Minister Ayman Safadi then charged that a group of plotters had linked up with foreign parties to destabilise Jordan, but declined to identify them.
After mediation talks, however, Hamzah voiced his loyalty to the king.
â€œPrince Hamzah pledged before the family to follow in the steps of the ancestors, remain loyal to their mission, and to put Jordanâ€™s interest, constitution and laws above all considerations,â€ the king said on Wednesday.
A probe into the events continues, the king added.
The crisis laid bare divisions in a pro-Western country usually seen as a bulwark of stability in the Middle East.
Jordan borders Israel and the occupied West Bank, Syria, Iraq and Saudi Arabia. It hosts US troops and is home to millions of exiled Palestinians and many Syrian refugees.
The kingâ€™s address followed orders issued by Amman prosecutor Hassan al-Abdallat that banned the publication of any information about the alleged plot to keep the security servicesâ€™ investigation secret.
The UN human rights office said on Friday it was concerned about a lack of transparency surrounding the alleged plot.