Saud al-Qahtani was fired as Saudi Arabia's royal court adviser on Saturday, Saudi state media reported.
The announcement came as the kingdom's state media said the missing journalist Jamal Khashoggi had been killed in the Saudi consulate in Istanbul, citing an official Saudi investigation.
Saudi state media also reported King Salman ordered the restructuring of the command of the general intelligence agency, under the supervision of Crown Prince Mohammed bin Salman (MBS).
Al-Qahtani, a law graduate, served as media adviser to MBS after holding several positions within the royal court.
He had previously worked as a legal adviser with late Saudi King Abdullah bin Abdul Aziz Al Saud's team in 2003 - when King Abdullah was the kingdom's crown prince.
Al-Qahtani then worked as an adviser to the deputy chief of the royal court, before becoming an adviser to the court in 2012.
Last year, when Saudi Arabia, the United Arab Emirates, Bahrain and Egypt severed diplomatic and trade ties with Qatar, al-Qahtani launched the hashtag #TheBlacklist, urging Saudis to add names of Qatar sympathisers to the list.
The Saudi-led quartet accuse Qatar of harbouring "terrorism" - an allegation Doha strongly denies.
Al-Qahtani had also tweeted that anyone who "conspires" against Saudi and its allies would be unable to escape trial.
Al-Qahtani has also been accused of using bot networks against political opponents and push government propaganda.
On Twitter, where al-Qahtani had launched vitriolic attacks against those he saw as the kingdom's enemies, thanked the Saudi government for the "great opportunity they gave me to serve my country all those years".
"I will remain a loyal servant to my country for all times," he wrote in a Twitter post on Saturday.
