The Tuesday evening Royal Gazette statement said that the monarch had sacked two bedroom section guards for 'evil actions' and 'adultery' and another two bodyguards for 'misconduct' and failing to comply with the standards of their ranks.
It further accused them of being 'lax' in their adherence to the rules, Efe news reported.
The four dismissals followed those of six palace officials last week, who were accused of severe disciplinary misconduct that caused harm to the royal service.
Since ascending to the throne in 2016, King Vajiralongkorn has taken more direct control of royal affairs and the crown's vast wealth and transferred two military units from the army to his personal control, Al jazeera reported.
Last week, in an extraordinary announcement, the King also demoted Royal Consort Sineenat Wongvajirapakdi, just months after granting her the title.
She was accused of being 'disloyal' and fomenting rivalry with Queen Suthida Bajrasudhabimalalakshana, who was married to the monarch in May, just days before his coronation.
Thailand's royal family is protected by a lese majeste law that makes scrutiny of the monarchy or debate over its role almost impossible inside the kingdom.
The 67-year-old King came to power after the death of his father Bhumibol Adulyadej - who was widely revered by Thais and seen as a figure of moral authority.
( With inputs from IANS )